Can I replace a concrete floor with suspended?
amber3d
| Posted in General Questions on
We are currently facing a dilemma in how to renovate/insulate our ground floor. Part of the ground floor is a suspended floor with covered ventilation due to raised external ground levels. The rest of the ground floor is concrete, with the living room previously having been a suspended floor. We’ve been advised that at the very least, the floor in the living room needs to be replaced as it has cracked and is damp near the walls. The kitchen area is part of an extension from the 1970s and has always been concrete.
Our plan moving forward is to replace the entire ground floor with a specific aim of minimising the use of concrete where possible. We’re considering replacing all the concrete with a suspended floor, incorporating telescopic air vents, and implementing a French drain around the perimeter due to the internal floor level being nearly level with the external ground. We’re also exploring the possibility of ducting for improved ventilation.
I am just wondering if this is a viable plan, particularly regarding changing the concrete floor in the kitchen to suspended. Any advice or tips I could get would be greatly appreciated and I am open to any other suggestions.
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Replies
amber,
When you say "suspended", I'm assuming you mean a conventional wood framed floor. Rather than that, which would involve building a crawlspace with all the moisture concerns and excavation that will come with that, consider a concrete-free slab. Here is one article, GBA has many more:
https://www.greenbuildingadvisor.com/article/concrete-free-slab
Hi Malcom, thanks for your reply!
Apologies, yes I do mean a conventional wood framed floor.
I've explored the option of a concrete-free slab and it was the route I initially intended to go but it seems like a niche concept and I've struggled to find much information about it other than a few articles here. Our extension features concrete block walls, while the rest of the house has granite walls. Do you believe this approach is suitable for us considering our house's construction?
amber,
I think a conventional wood floor is probably the most complex solution, as unless it sits on fill (which is really just a variation on a concrete-less slab) you would have to excavate and build a crawlspace underneath, with all the attendant work that requires. The use of concrete-free slabs is driven by the desire to reduce carbon emissions from construction. If that's important for you then I would consider them. Their use does come with complications, both in permitting and execution as they are not very common. The simplest solution would be to remove the existing slabs, deal with the moisture issues, and replace them.
Generally, when people talk about flooring, they are talking about the finished surface not so much about the unseen structure.
A crack in the finished surface generally does not require sub flooring/structure to be replaced.
What is wrong with the current sub flooring/structure?
If the old joists are so rotten that they can no longer be used you must deal with the moisture problems that caused the failure.
Concrete failure would almost be unheard of making it very unlikely that the concrete “need” replacement.
“The rest of the house has granite walls” This sounds like a most unusual home. Solid granite wall seems very unlikely granite tiles seems plausible.
Interior French drainage systems almost always require a pump to remove the water. Since the it generally rains when the power goes out every power failure becomes very concerning. Will the power be restored before the house floods or not. If at all possible put the drainage on the exterior with a gravity drain to daylight.
Would this home be in the USA?
Walta
Hi Walta,
Our home is a 130-year-old farmhouse in Scotland. The concrete slab in the kitchen is structurally sound but uninsulated and unfortunately, there's no room to insulate on top. The damp/cracked concrete is where there used to be a suspended floor, but at some point along the line, it has been poorly filled with concrete , again without insulation.
We've recently had a section of the wall removed and they are 100% 500mm granite walls, which is a common construction in our area.
Thank you for any advice or insights you can provide!
amber,
My advice was based on the assumption we were talking about standard North American houses which are wood framed on a concrete foundation. Your options for an old house in Scotland maybe very different. I would try and get some local builders to look at what is possible.
I assume you mean granite blocks?