I am about to start an extension of about 4mx9m in my garden but i am confused of what to do with the ground in term of foundation since the whole of ground is concrete of about 4″ to6″ thick . Some of the builder i contacted are of the opinion of breaking the concrete up and about dig a trench to the depth of 3-4feet and start from the scratch while some just wanted to do ablock framework on the concrete ground and pour concrete in between as base. could any body enlighten me on most economical durable and safe way to do this and for long lasting hitch free building
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Where do you live? Why is the concrete there (it's a bit thick for a simple patio).
Normally it would not be wise to use the slab for a foundation, especially an extension of an existing foundation (that isn't also on the slab), since the slab will tend to rise and fall with frost and moisture changes.
But it would probably work out in a relatively warm, arid climate, and might work if the slab is the former foundation of another building.
Certainly digging through the slab and installing a conventional foundation is the safest approach (though also clearly more expensive in the short term).
Welcome to BT, first off.
May help to know where you are located--your mixed use of metric and english measurements suggests many places.
We have folk fere from NZ and the antipodes as well as closer to the Midlands, and Canadians east, west and center.
Why is this important? Well, building terms are very regional--knowing the region can (only can) help decipher things. For instance, you could be referring to "laterite" when you say "the whole of ground is concrete" (or, that could be a garden slab in parts of the UK).
Location is also important in knowing if you have a municipal authority to whom you must answer (the term-of-art is AHJ, or Authority Having Jurisdiction).
Location is also important if you are translating the web site into your first language, too.
So, if you will look to the upper right of the screen, there should be an "Update Profile" button (there is no outline for the button); which can help us all.
Ah, one more question: You say "extension," is this meant to be an addition to the existing living space of the house--or are you enlarging a paved area?
Thanks for your reply ,Iam located in Dublin in Ireland my project is an addition to an existing house and the concrete is a poured concrete that is been there for more than 6years and not intended for another building but to coverup the ground.
Yeah, they should cut through the slab and put in a regular foundation.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Absolutely.SamT
Thanks for your reply
No problem, just wanting to help out.
I'm not familiar with building practices in Eire, you may have a Planning Department, or a Council, that has power to approve (or disallow) certain building practices. If that is the case, then they will be your best source for "right way" to do things.
You probably ought to consult an engineer, who can address the issues of how best to tie into the existing foundation. Such work can be simple, and it can also be complex (and, far too often in remodel/additions work-both <g>).
These are mere questions of curiosity. Does your present house have a full basement? Or, a crawlspace; or, perhaps, a slab-on-grade? Is this a wood frame house, or a masonry structure?Occupational hazard of my occupation not being around (sorry Bubba)
Your advice is well understood and i will following the standard pratice of digging the trench to make the foundation . The existing house has a full base and the house is mansory as well as the intended addition building .once again thanks for your help. As i will be taking this project as a semi DIY you might hear from me again if i get into any doubtful situation.
Yes, in general when extending a foundation it's best to make the new foundation fairly much identical to the existing (providing the existing is adequate in the first place). That way they're most likely to move together with any settling, frost heaving, etc.
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
Your advice is well understood
Well, that's good news. While my ancesters were evicted from Skye or Lewis, a bare few hundred kilometers for you, I'm sore afraid central Texas buliding lingo and argot would translate but poorlt into the Gaelic <g>.
While stop orders from town councils, sadly, would all too well translate <sigh>.Occupational hazard of my occupation not being around (sorry Bubba)
Where in Dublin? In the north suburbs around that new highway, or in the southeast part towards the ocean? I assume not in the downtown area.
Irish building practices are considerably different than the states. You guys love masonry for your structural support, we like wood (or metal). (Of course, we know the Brits took all of your trees.) And those foam pieces you slip in between the two layers of masonry over here would draw funny looks. And we won't even go into the electrical or plumbing differences.
You've received some excellent suggestions so far. And we are extremely interested in these different construction methods, so keep us informed!
I've also recently read that living in Dublin has become one of the most expensive places on the planet to live.
I am very confused by your question. This is probably because of a language problem. I can't tell if you want to extend your garden into an area that is covered by concrete ... or if you want to extend your house into part of the garden.
I will assume that you want to extend the house. First of all, in most circumstances, a building has only one foundation. This is because a foundation does two things: it spreads the weight of the house over the entire area, and it ties the house into one solid mass. It is very important that the entire house move together, as one piece - and not as two or more parts, moving in different directions.
When you want to 'extend' a foundation, the new foundation needs to be able to support the weight ... AND be tied firmly to the old foundation. When the house moves up, or left .... the addition also needs to move up, or left.
This is the reason behind so many failures ... the connection between the different parts fails, and major damage is only a matter of time.
Without knowing the details of your existing slab, and home, I suspect that the contractor who wants to start over is being more responsible .... while the guy who just wants to pour a puddle of concrete is only interested in the thing lasting until the warranty period is over.
I would recommend you hire an architect- they are supposed to know this stuff.