Suspended timber floor v Concrete

13 Nov 2006
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United Kingdom
Happy New Year all. I expect this question has already been asked in some form or another, so I apologise in advance should i be correct.

I have been asked by friends to price for laying a new solid timber floor 200mm x 22mm random length hardwood grade t&g, it can be floated or secret nailed. So the conundrum is this, they have had their kitchen and the scullery knocked into rather large room. The existing kitchen is suspended timber floor whereas the scullery is concrete, poss concrete and screed. However the concrete/screed floor is higher than the timber boarded floor in the kitchen by about 2" to 1".

Now this is where I need advice, I see I have options here, firstly I cannot raise the timber floor to suit the concrete because this would cause big steps in the door ways into the kitchen. So I reckon I can either remove the "screed" lay down a dpm then batten and ply the concrete to bring it to the height of timber floor should the new floor be secret nailed, or if I were to float the new floor then I could remove existing screed have the floor re-screeded to align with height of suspended kitchen floor and bobs your uncle.

I really am not sure, so any advice from the experts would be great, thank you.
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Before you do anything, I would convince your friend to switch to wood-engineered boards. 200mm wide solid is rather wide and absolutely too wide for in areas where there is more moist = kitchens!
Thank you Wood You Like, I was more sounding out the "what to do with the concrete floor situation" but you have a very valid point of which I will put forward, Cheers
Hello again, I know there are a lot of experienced and knowledgable individuals that use this forum and this why i ask again if anyone can give me advice on my above post from the 3rd January, what I am trying to avoid doing is giving myself more work than is neccasary. Thank you.
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As you can't raise the suspended floor to the level of the concrete you really don't have much choice but to lower it at the other end. My concern would be regarding ventilation as even if you put a dpm under the new battened and timbered floor there is no way for any air to circulate so a build up of condensation (in a kitchen??) would have no means of escape. I think I'd be inclined to take it down lower and put some pir insulation under it, with a dpm as well and then float the new floor.

Its a tricky one without seeing it but I would probably also put a layer of marine ply or t&g moisture resistant chipboard under the hardwood just to make certain no damp got through.

It would be worth investing in a damp meter to check the moisture levels as you expose the different areas under the existing floors.

I had a similar situation a couple of years ago on a renovation project and ended up removing all the concrete floor and digging down severalinches so that I could then put in a dpm, 4-6 inches of concrete, 2 inches of insulation, t&g chipboard and then a hardwood floor covering. It was pretty damp and the dpc on the house was almost non-existant and it certainly exceeded the budget for that part of the works, but I wouldn't have wanted to do a shoddy job that would cause problems within a couple of years.

A friendly architect, surveyor or builder should be able to advise as it does sound like something that needs to be examined closely.

Good luck.
Hello Jackonthecoast, the flooring is no longer hardwood it is softwood in the form of 122x18mm PTG this will be secret nailed to the exisitng timber floor which is well ventilated. I think my only choice with the concrete and screed floor is to gun it all out and extend the suspended timber floor through on sleeper walls and joists cover in T&G mositure resistant chipboard or marine ply, and install new air bricks, then lay new floor. What do you reckon? Thank you for your time.

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