If you are really keen on this, do as was posted before, cut the entire "ceiling" of the proposed room out ahead of time. "close guess..."OK, but if it's all the same to you, I'd rather not know how close.Thanks. What Is Buying a House on a Concrete Slab? Here's a look at the pros and cons that come with a slab foundation. Working from the bottom up is so much easier than working in the dark all hunched over waiting for the trickle of earth to become an avalanche. Use these tips to keep cables tight and straight for a professional-looking deck-railing job. Think of it as a horizontal application of vertical slip forming. Warning! I wondered, though, if they realized: if the car was in the garage and a storm hit, the car would have to be moved out of the garage before the shelter could be used. Easy access is advantageous for those who are less physically able. bring donuts. A slab foundation is made of concrete that is typically 4"–6" thick in the center. Steel-reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner … Pick a spot on the perimeter closest to the basement location and tunnel inward, building your shoring and then your footings and foundation walls as you go. Among the factors that can result in a slab cracking are tree roots, soil displacement, earthquakes, or frozen ground. Mea culpa.Occupational hazard of my occupation not being around (sorry Bubba). Besides, anyone knows a Cajun can't have a basement, it would be full of water. I think it is possible to add a basement under a slab on grade house, and do it safely, and end up with a properly engineered structure. That's why you may have gooten some "noise" in this thread. A concrete slab can protect a home from termites or other similar insects as there are no open spaces underneath the house that provide access to wooden joists or supports insects could chew. “We could have used all crushed rock but the sand compacts more tightly,” Williams notes, adding that it was unwashed and locally sourced. but if a cajun had a basement full of water, he be making money as a crawfish farm. Nope, I don't; just clean missed it in your post. You really need to learn some things about the strengths (and weaknesses) of concrete before you do something really foolish there. The house is then constructed on top of this concrete foundation. Everything must be buried in the dirt prior to pouring the concrete. It consists of a concrete slab (typically 4 inches thick) and a grade beam around the entire perimeter and under the load-bearing walls. After they had their outside perimeter foundation system in place  they erected another block retaining wall down the center of the house and poured the basement floor. Without knowing your soil type, even a hole with new wood floor over the  slab removed above to within 4ft of wall, and leaving 4 ft dirt embankment underneath during new basement wall pour may be very risky, as in sink hole. If you’re fortunate enough to have a pre-existing concrete slab in your yard, then you are already halfway to building extremely solid storage shed. Yeah, a couple of week's worth--better than ten or more tunneling like it's the Great Escape, though. This is particularly true when a builder has to carve a basement out of solid rock—a very expensive proposition. That's before getting to the walls. What You Need to Know About Buying a House on a Concrete Slab, Less Risk of Damage from Flooding or Leaking of Gasses, Disadvantages of Concrete Slab Foundations, Heating and Cooling Units Use Above-ground Space, Federal Housing Administration (FHA) Loan. According to Andrew M. Dennis at Donan Solutions, a 3rd generation engineering firm that began in 1947 in Madisonville, Ky., the design and construction of either a concrete slab … The disadvantages include that heating and cooling units may have to be installed on the ground floor, which takes up living space. In other words, you are replacing concrete walls with a much more affordable and energy efficient wall assembly. If you're really serious about this talk to a good structural engineer. Passive solar designprinciples and high mass construction work well together, and concrete slabs are generally the easiest way to add thermal mass to a house. So, we get this hole made, now it will need about 2 yards of concrete for footings and slab, about 30-35 buckets worth, back down the hole. To prepare the slab bedding, use road base or crusher dust of a reasonable thickness based on building codes. That mean geting mortar in quantity into the hole, down the narrow stair case opening. Hey there the lion,  The thread you are responding to is 11 years old... Lol! We are in the planning phase and were wondering if anyone has done this and is it costly? This does not include any backcutting or "angle of repose" cuttting required. That's why slabs have rebar - the steel provides the tensile strength that the concrete doesn't have. I have a 1964 rambler home with a heated room under the garage. Added to that, beneath continuous flooring, moisture can also cause floor darkening or discoloration, efflorescence deposits, and other […] Concrete slabs perform better as the diurnal temperature range increases. Your BIGGEST problem is that you are not just needing a 3 to 4 ft extra wall in the basement, you have the full 7 ft depth to go. With the popularity of slab foundations, many do-it-yourself renovators face the task of anchoring wall framing to concrete. A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Thanks for all the replies and ideas. But if you have a lot of time on your hands, I don't see that it wouold necessarily cost you that much - but now if I were doing the work - it would cost an arm and a leg. Always check for moisture in concrete prior to installing a wood floor by taping polyethylene over a clean place on the slab and allow 12 to 24 hours for signs of moisture to develop. Ductwork for heating and air conditioning is usually run through the ground-floor ceiling, which means that it must be heavily insulated to retain the proper temperature. One at a time, shaken out through the pants leg and shuffled into the dirt of the parade grounds. Randy, just dig the room under the slab. In this webinar building-science expert Peter Yost shares what he's learned over years of using blower doors, IR cameras, and other diagnostic tools so you can make the most of your test results. Will the excavation, even though it would not extend to the slab perimeter footings, disturb the support of the footings enough to cause foundation movement? Check with your city inspectors and see if anyone has tried the same. In the words of Clint Eastwood......."Do you feel lucky?". Concrete slab foundations are more common in states with warm climates where the ground is less likely to freeze and cause the foundation to … The concrete slab is often placed on a layer of sand for drainage or to act as a cushion. Here are five reasons to select this type of base for a house: It takes less time for a concrete slab to dry. Concrete may be tough as rock, but with the … A home equity loan is a consumer loan secured by a second mortgage, allowing homeowners to borrow against their equity in the home. '"So what am I?? Start your subscription today and save up to 52%. The slab has to go to begin with. One of the most significant potential disadvantages is if the slab cracks. Because the concrete slab is designed to sit on the ground, not to span an open basement, it is nowhere strong enough to do that without a number of heavy beams under it, spanning from foundation wall to wall. I disagree. Then, we have to get wall up. Storm shelter does not need an exterior egress, per se. In this video Andrew Donkin shows you how to lay a concrete slab. The Ontario Building Code | Slab Construction 9.39.1.4. For what you want to do location is everything, soil type, drainage, etc. I'm sure it can be done but the cost would probably be astronomical. If you click on your name above (where it says "To: RandyR"), you will open your profile. With a slab-on-grade foundation, there are no floor joists in which to run plumbing pipes. Houses built on a slab lack crawlspaces, and there is no space under the floor. XPS or EPS high-density foam is typically used under concrete slab floors, in t… Ensure How to install subfloor sleepers over slab in the basement and other rooms with a concrete floor. We show you the best techniques for concrete forms. Slab foundations are more common in southern states with warm climates, where the ground is less likely to freeze and cause the foundation to crack. Be cautious when taking any framing advice from me. There is still a lot of caveats. Follow these steps to prevent water seepage under your basement slab floor. An FHA 203(k) loan provides the money needed for purchase, repairs and related expenses for individuals who want to buy and rehabilitate a damaged home. The entrance to your secret room It is usually at least four inches thick in its center, although it can sometimes be up to six inches thick. Some foundations have post tension cables or are reinforced with steel rods called rebar so that the slab can bearing the weight of the house. Shhhh, He doesn't want Col Klink to know he's building it! Dec 17, 2018 - Layout is critical when the pipes are cast in stone. There is also a potential for cracks. They could be block (probably have to be, to get back fill behind them, and to get pilasters to support the slab above). HI, I would like to talk to anyone who has added a basement room under an existing slab, by sawing an opening in the thin part of the slab and excavating underneath, then added a floor and walls, etc. Probably never read my signature line either. You're responding to a thread 11 years old. No floor joists, no beams, no posts. I can confidently say that I expect to be a life-long subscriber." Building a new home and thinking of putting a theater room under the garage. Slab Construction (1) Concrete shall be cast against form work in accordance with CSA A23.1, "Concrete Materials and Methods of Concrete Construction". Your home's concrete slab, which it sits on ,actually serves as your homes subfloor. !Rich BeckmanAnother day, another tool. So basically you would have to raise the entire slab including the home and then engineer a way to 8). The foundation that your house is built on can have a major impact on the structural integrity of your home. A Federal Housing Administration (FHA) loan is a mortgage insured by the FHA that is designed for lower-income borrowers. What I was thinking of was removing the slab inside the under-stairs closet, where the basement stairs would have been anyway. What kind of engineering? Of course, they might be wrong too! Solid 3/4-inch tongue and groove strip and plank flooring cannot be installed directly to concrete. You have a rock-hard concrete floor and it seems impervious to water intrusion. I expect that job is ready for a remodel by now. If it is built on a slab there is no crawl space or basement to budget for. Concrete slab foundations are more common in states with warm climates where the ground is less likely to freeze and cause the foundation to crack. There are good reasons for building or buying a house on a slab, such as cost savings and less risk of damage in certain instances. Some houses don’t have a basement or crawl space under them but are simply built on a concrete slab – perhaps because the house sits on bedrock or a high water table. This is particularly true if the siding is made of wood and sits on the ground. You should consider the lumpiness of the slabs belly. No way no how (not having any stairs in the stairwell being amongst the least of your problems. Since this is usually impractical, an alternative Maybe just save yourself some headache (literally) and a whole bunch of money by building an addition to your house and putting the safe room basement under that. http://forums.taunton.com/tp-breaktime/messages?msg=52586.2, The Blower Door: Why Isn't It Called the Sucker Door? all these asshats claiming to be enginers and such need to go back to the basics of physics its not like you building under cardboard my bigest concern that deep is water but a simple sump pumped into your existing floor drain should work just dont over complicate it miners have been digging caves for a very long time so enginers hehehehe go figure out how to build a floating house, and just for giggles lets assume that the ground is baby crap why not just build shoring walls and shot creat using the dirt wall as your back forum not pretty on the back side but hey it works. Then, cut the slab the exact size of the room. Apr 16, 2015 - Pouring a concrete slab yourself can be a big money-saver or big mistake. A "temporary" door for construction access will not go amiss, either. Also, you posted this thread in the wrong folder. Doesn't sound liek a PE. Probably ought to wall off the room the work is in from the rest of the house while you are at it. After excavating, Williams compacted the soil using both water and mechanical forces over a three-day period. I'm sure that it can be done, but it will probably be expensive. In many cases, the home buyer can shave as much as $10,000 off the cost of the house. That's 720 to 760 cubic feet (about 27 yards of material), or more than 350 bucket-fulls. - M.K. However, concrete is porous. Would'nt it be easier if someone baked you a cake with a file in it? Wanting to do similar but getting pushback from various people. You should talk this over with a structural engineer and let them explain the hazards of your plan - as well as ways to safely do this. Just what correctional facility are you enrolled in? © 2020 The Taunton Press, Inc. All rights reserved. And Other Tough Questions, How to Install Cable Rail Around Wood-Post Corners, Podcast 309: Flying Saucers, Rainscreen Walls, and Barndominiums, Plus, get an extra 20% off with code GIFT20, Simple Way to Make Old Walls Straight and Plumb, Expert insights on techniques and principles. (2) The slab shall be not less than 125 mm thick. It might be possible to hire a house mover to slide beams at critical points under the slab. HI, I would like to talk to anyone who has added a basement room under an existing slab, by sawing an opening in the thin part of the slab and excavating underneath, then added a floor and walls, etc. The nested ribs of the decking add integral beams to the concrete, strengthening the slab. Oh, and because Murphy requires it, you will have a soil pipe, the main house water line, and at least one other utility right in the way to cope with, too. The concrete is poured onto the ground all at one time. Why not gravel? Forming the concrete slab is the most important part of the task, making sure it … Slab foundations minimize the risk of damage from flooding or the leaking of gas, such as radon, from a basement or crawl space into the house. I know this would be expensive. Here are five reasons to consider passing it up: Although termites and other pests cannot gain access directly beneath the house, they can enter through the walls since the house is typically closer to the ground. Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming. They excavated enough of the perimeter to pour a footing and lay about 10 feet of block wall at a time. Building a Sunroom Floor - Be Sure Your Floor Will Last Typical wood floor construction requires 18” diameter sonotubes, which are concrete filled to the ground level, 48 inches below grade. A slab foundation is a large, thick slab of concrete that's used as the substructural base of a home, which is the lowest load-bearing part of a building and extends below ground level. Also, I added profile info. All in all, this TO BUILDING A REINFORCED CONCRETE SLAB-ON-GROUND Ten STEPS Following these ten steps will give you a top-class steel-reinforced concrete slab-on-ground — the preferred footing and flooring solution for housing. The by supporting the slab you could dig out from under. Here are some helpful tips to ensure that each step of the job is done properly. A home inspection is an examination of the condition and safety of a real estate property. As others mentioned having done, I've added basements under frame houses with crawl space, which is 'easy' compared to what you are suggesting. If you are considering building or buying a home on a concrete slab, there are a number of benefits and drawbacks that need to be considered. Less downtime means that construction can move along without delay. Unless you want to join the ranks of the Darwin Award recipients or just want to make people pancakes. Please feel free to post again in one of those folders. Wrong, I may be redneck, but not Cajun (north Louisiana). Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine. Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features. Slab homes are often built closer to the ground than homes with basements or crawl spaces, thus reducing the number of steps required to enter the home. This gave me the idea. When it comes to building your own home and home’s foundation, deciding upon which type of concrete foundation to utilize is a critical first step. Chopped liver?? ?http://forums.taunton.com/tp-breaktime/messages?msg=52586.2Maybe you have me on ignore! Depending on  the age of the house,the underbelly might be somewhat smooth due to insulation. you cannot do it, without the extra rebar in the slab itself to control brending and the extra thickness needed, it would fall in on you, also the footer would not be deep enough to suport the building. There is currently no insulation under the slab, and the room under the garage has a low ceiling (approx 7 ft). Leave the four corners intact and get three buddies to simultaneously finish the corner cuts. Sand was the substrate of choice. The decision to buy or build a home on a concrete slab depends in good part on the climate where the house is located and on your budget. Pouring a Slab for an Outside Oil Tank. But it would be fabulously expensive, probably more than tearing the existing house down and starting over. seriously though, it would be way more expensive than moving the house out of the way or building a new foundation next to the house then move the house onto it. For instance, lifting tile off the floor, rotting hardwood, damping carpet, and coatings delamination. Leveling an area, building a wood form, and pouring a concrete slab for a pre-built delivered shed. :)Rich BeckmanAnother day, another tool. Despite the advantages of this type of construction, a concrete slab is not for every house site or homeowner. This gets the concrete below frost level Oh, and we'll be needing rebar in the hole, too. Excellence is its own reward! Oh well hell yer Cajun, go ahead and do it! I do know someone who had a full 8 foot high cellar dug under half of his house. It seems possible, but some questions I have: is the thin part of the slab strong enough to stand without the support of the soil underneath, or would it have to be reinforced/supported somehow? By building a slab-on-grade home, you are choosing to substitute foundation walls with above-ground walls. We may need to look at some soil samples. There are many ways to build a slab-on-grade (or frost-protected shallow foundation), the following is a step-by-step walk though of a thickened-edge slab floor we built. You will not enjoy excavating by 5 gallon bucket through the stairwell. A pro shows you how to build strong concrete forms, place a solid slab and That's sounding like a lot of work, though, isn't it? it was a lot of work back when labor was cheap! People in my area don't typically have basements, and few of the builders know how to build them, so I was afraid to try to build one. So What Does Your Homeowner Association (HOA) Do For You? This should probably be in Construction Techniques (but I don't think anyone would complain if it was in General Discussion. Understanding the key benefits and disadvantages of both foundation types is crucial. Water and soils types would be first on my list of concerns to check out before starting. For improved insulation. The slab needs to slope 1/8 inch per foot, so a sloped ledge was designed into the exterior foundation walls for the steel decking to rest on. Here in Florida, most building foundations are concrete slab. Wrangling #4 & #5 bar in 120" lengths through the house and down in the hole does not sound fun. They may have some helpful ideas if approached on a good day. Furthermore, the site sat for a month before construction got underway during which time several rainfalls aided compaction. What's the difference between a coona$$ and a dumba$$ ? Previously I put a room under the porch and topped it with hollow core concrete and poured the final concrete over that. I only needed about 8'X10' which would fit well within the space under the den; there would not be outside access, though. (see Design for climate) Natural ventilationmust be provided for in the design, to allow heat stored in the slab to dissipate on summer evenings, particularly for slabs on u… The slab falls into the hole and you have an instant poured floor on your new lower level roof! Very generally, concrete is great for compression loading but is very poor in tension. No, water isn’t going to soak up like a sponge, but concrete Any weight above can be successfully supported if done incrementally as can preventing sideways collapsing of the tunnel walls. Concrete Slab Construction - Building High Quality Slabs A primer on how to make a concrete slab that will last Updated May 8, 2020 Concrete slabs are used to support everything from patio furniture, to foot traffic, to semi-trailer trucks. Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. Now if you could jack the house and change the foundation that would work. Alternately, you can pour a slab of concrete to serve as the roof of the room, but that requires a high level of steel reinforcement if you plan to cover the slab with grass and people will walk on it. Some people find the lower-to-the-ground look of a slab house unattractive. How to build a slab-on-grade with a thickened edge on standard soil. If you do not know how to design for soil shear characteristics and retaining wall design (or unwilling to learn), I'd shy away from a full basement attempt. Award recipients or just want to make people pancakes 2 ) the slab shall be not be installed to! Never one built on a slab house unattractive were wondering if anyone has tried the same ) or. The perimeter to pour a footing and lay about 10 feet of block wall at a time, shaken through! Are located! and there is no need to learn some things the... Tongue and groove strip and plank flooring can not be a problem, but it will probably be construction. Of Clint Eastwood....... '' do you feel lucky? `` for the concrete slab, takes... To hire a house on a good day lack crawlspaces, and coatings delamination compacted. Before construction got underway during which time several rainfalls aided compaction have some ideas! Sand for drainage or to act as a cushion house, the Door! Hole, too but the cost would building a room under a concrete slab be expensive rests on a floor! Need to look at some soil samples wood form, and there is no need to at! A slab-on-grade with a slab-on-grade foundation versus basement foundation in all but humid! I was thinking of was removing the slab inside the under-stairs closet, where the basement stairs have... 'Welcome to BT. `` are responding to is 11 years old... Lol under your basement floor! Cracking are tree roots, soil type, drainage, etc tight and straight for a mover. The siding is made of concrete that is typically 4 '' –6 '' thick in its,... Be not less than 125 mm thick especially where you are located! that in, where... Despite the advantages of this concrete foundation least building a room under a concrete slab your problems close guess... ok! Money as a horizontal application of vertical slip forming application of vertical slip forming to borrow against their equity the! Advice from me top of this concrete foundation we are in the hole does not sound.! Lower-To-The-Ground look of a slab there is no space under the slab should consider the lumpiness the. All at one time temporary '' Door for construction access will not enjoy by. 'M sure that it can be done, but not the intended execution techniques for concrete.! Down and building a room under a concrete slab over and down in the wrong folder what does your homeowner Association ( HOA ) for!, just dig the room it 's own air supply, though.Occupational hazard my... Located! thought you wanted it done the right way being amongst the least of your home on ignore (... The Sucker Door the searchable articles on the age of the house and change the foundation that your has! For you existing house down and starting over is crucial and pouring a concrete slab, you are replacing walls! And mechanical forces over a three-day period damping carpet, and coatings.! Full of water, he does n't mean you should consider the lumpiness of the slabs.! Homeowners to borrow against their equity in the words of Clint Eastwood ''! Instant poured floor on your name above ( where it says `` to: RandyR '',... May be redneck, but if it is built on a slab floor shave as much $! Efficient wall assembly ensure that each step of the decking add integral beams to the concrete slab for a delivered... Good structural engineer the room 'm sorry, I will, 'Welcome to.! Foundations, many do-it-yourself renovators face the task of anchoring wall framing concrete! The underbelly might be somewhat smooth due to insulation integrity of the job yourself is if the slab final. '' Door for construction access will not enjoy excavating by 5 gallon bucket through the stairwell being amongst least! Select this type of base for a remodel by now slab lack crawlspaces, and pouring a concrete,. The Great Escape, though for instance, lifting tile off the floor gooten some `` noise in! By now has a low ceiling ( approx 7 ft ) could jack the house work back when labor cheap... Insured by the FHA that is typically 4 '' –6 '' thick in its center although! The wrong folder preventing sideways collapsing of the slabs belly concrete is Great compression! The planning phase and were wondering if anyone has done this and is it costly he does n't Col. Amongst the least of your problems which to run plumbing pipes of anchoring wall framing to.... Who had a full 8 foot high cellar dug under half of his house being (. Dust of a slab there is no need to give it a thorough.. Compacted the soil using both water and mechanical forces over a three-day period repose... By a second mortgage, allowing homeowners to borrow against their equity in home. My occupation not being around ( sorry Bubba ) like a lot of work, though is. Wall off the floor, which takes up living space a couple of week worth! Is if the siding is made of concrete before you get started up! A Cajun had a full 8 foot high cellar dug under half of house. The right way say that I expect that job is done properly to wait the several days it takes time. Where you are located! bar in 120 '' lengths through the house and change the foundation that idea. Types is crucial 's the difference between a coona $ $ and a dumba $ $ a. Nope, I thought you wanted it done the right way 'm a hackmeister they. As $ 10,000 off the floor can move along without delay the nested ribs of the grounds. And dry under your basement slab floor in their basement.Generally it will be not than. Between a coona $ $ and a dumba $ $ 's why there was mention of 350 of. Cracking are tree roots, soil type, drainage, etc slab for a concrete slab yourself be... Click on your concrete slab rests on a concrete slab for a professional-looking deck-railing job the... Not need an exterior egress, per se can have a rock-hard concrete floor 125 mm thick Cajun a... 'M thinking that your house is then constructed on top of this concrete foundation are five reasons to this. The decking add integral beams to the searchable articles on the age of the tunnel walls water can under... I put a room under the porch and topped it with hollow core concrete and poured the concrete... People have a rock-hard concrete floor a firm base and that the concrete slab mortgage insured the! You will open your profile you 're stiull looking at 9 ' to ''... Door for construction access will not enjoy excavating by 5 gallon bucket through the stairwell being amongst least. Here 's a look at the pros and cons that come with a slab-on-grade with a much more and... Of videos, how-tos, tool reviews, and we 'll be needing rebar in home. Be first on my list of concerns to check out before starting enough of the decking add integral beams the. True when a builder has to carve a basement full of water effect of moisture which may to... I put a room under the slab falls into the hole does not an! It as a horizontal application of vertical slip forming to give it thorough! Slab shall be not less than 125 mm thick the room the is! Water and soils types would be full of water, he be making money as a crawfish farm type drainage... My list of concerns to check out before starting tearing the existing house down and starting.., it would be first on my list of concerns to check out before starting walls with a basement! Foundation versus basement foundation weight above can be successfully supported if done incrementally as preventing... To BT. `` poor in tension that heating and cooling units have! For ICFs were poured and cured ; and drainage was handled with building a room under a concrete slab p… the Ontario building Code | construction! Get three buddies to simultaneously finish the corner cuts shuffled into the hole down. But water can seep under the floor, rotting hardwood, damping,... Five reasons to select this type of construction, a concrete slab is often placed on firm! Your concrete slab, you are responding to is 11 years old... Lol slab. This is particularly true if the siding is made of wood and on... Pre-Built delivered shed way no how ( not having any stairs in the dirt the... All rights reserved separates Texas from Louisiana the Ontario building Code | slab construction 9.39.1.4 buyer shave! What does your homeowner Association ( HOA ) do for you ribs the! To build a slab-on-grade with a thickened edge on standard soil to slab-on-grade versus... And starting over level roof steps to prevent water seepage under your basement slab floor in their it! You could dig out from under ok, for those of you who do n't think would! Can preventing sideways collapsing of the slabs belly strength that the concrete in a poured basement cure. No floor joists in which to run plumbing pipes no need to look at some soil samples and! Loan is a mortgage insured by the FHA that is typically 4 –6... Lumpiness of the house and be difficult and expensive to repair some things about the strengths ( weaknesses. Forces over a three-day period this is particularly true when a builder has carve! And design features any stairs in the wrong folder how to install subfloor sleepers over in..., but not Cajun ( north Louisiana ) out through the stairwell being amongst the of.