solid oak floor problems

Hello there, i hope you guys can help me.
I’ll try to give you as much info that i can, but sorry if i go on a bit !!
I’m a general builder, and I’ve been dealing with some damp issues in an old cottage ( the usual stuff damp walls and floor etc).
There’s a solid oak floor laid to the lounge/diner, this had a section that had cupped quite badly this section is 4 boards ( 150 mm wide by 22 mm thick boards ) wide and 7.5 m long but these 4 boards are split in the middle with a nib of wall, so there are 4 boards either side of the wall 3.6 on each run, if that makes sense!
There was no expansion gap to this edge, in fact the boards were imbedded into the plaster and render, plus they were starting to go rotten on this edge ( you could push a knife into them).
My first thoughts were there’s no expansion gap and the wood swelling has caused this heaving.
I removed the skirting and these boards, they where stuck down to the concrete slab with a trowel on adhesive, when i lifted the boards there were areas that were wet, drops of water to the under side of boards in isolated areas, it looked like they were trapped between the adhesive and the timber.
When the damaged boards came up it lifted areas of the concrete slab, so i patched these up, i then blackjacked any holes behind the skirting that needed it and patched them up too. When this was all dry i blackjacked the exposed slab and up to the top of the skirting line.
This outside wall is a solid 9 inch wall thats been injected, but on the inside this is at the point where the wall meets the slab and the oak floor. The walls above the floor in this area are showing no signs of damp so I’m assuming that the damp injection that had been done some years ago is doing its job.

I couldn’t find any kind of flooring to match this off the shelf so i had to get some cut for me.
I got 10 x 3.6 m lengths of canadian white oak, I fitted these in full lengths either side of the nib of wall. i had to get an extra one for each side because where the existing boards had been left for a while the next one along had started to curl up. I left an expansion gap around the edge, refitted skirting, then stained and varnished etc, i couldn’t believe that i managed to actually match up the colour by building up layers of stain. All was done, everyone happy- until i got a call a week later. When i saw it i couldn’t believe it, it was worse than before! it had cupped really badly along the same place as last time heaving the two boards where they join and all the other new boards had a very slight cupping to them.
After looking at this forum i realise that i didn’t leave the boards to climatise in the room, and that i didn’t use the same adhesive , i just used a no more nails equivalent.




There is no DPM or insulation under the slab plus the internal floor level is below the outside ground level. Blackjacking the floor and skirting area should stop any damp coming through i would hope but I’m not sure about the line from the blackjack to the existing adhesive.


Questions : Would the water drops in between the adhesive and boards be condensation ? Could this return?
If i re-lay this section is it likely to do the same again ?
The floor is glued down and there is no expansion that i can see to any wall but this was the only area that had cupped. Do i need to go around the whole floor and cut an expansion gap?
I didn’t think that it was correct to lay this floor with no DPM or insulation etc. Was this floor laid correctly in the first place?
Am i totally to blame for it cupping the second time, or would this of happened down the line, just a little slower ?

I really want to sort this out for the customer and to give her the best information and advice i can and i’d like to thank you guys in advance for any help you can give me.

 

the first thing to do was to run a damp test mate! wood + damp= fail floor in my opinion

 

the concrete really needs digging up and replacing with a working dpm, after minimum of 4 weeks you can surface dpm, prime then do a floorlayers screed pref waterbased or a latex with high compression strength over 30 nm, the floor can then be bonded to the subfloor. The lack of expansion gaps wouldn't create cupping or tenting that is definately a moisture issue but the lack of expansion gap coupled with the moisture problem could cause it to expand massively either pulling the concrete out of the ground or pushing through a structural wall quite easily, do a proper moisture test and get a hygrometer reading for the concrete and the air and a moisture reading from the wood then we can give you more detailed advise matey

 

Tank the room...

 

then install a good quality engineered product...

 

yeah that bit too

 

have done this on a few occassions... ensure to use good tanking product, bring it up the wall as high as you can, allowing the new skirt to cover it, then simply float install the eng., fit the skirt & happy days... ps - ENSURE all tanking joints are sealed up nicely...

 

some of schluters gear is great for tanking

 

Thanks guys for your reply’s its much appreciated.

So it seems the general consensus is the old floor needs to come up as it was never laid correctly in the first place.

When the floor comes up I’m guessing its going to lift up some of the slab underneath. If money was no object then the whole slab would come up but sadly this isn’t the case. Can i use a self leveling screed to fill any holes and to level ?

Can I use a standard 1200 gauge DPM ?
I’d well lap and tape any joints and lap up behind the skirting.

Is there any type of insulation you’d recommend as there is nothing under the slab? This would have to be slim though, i can raise things up a bit but not massively, i guess I’m looking for it all really, slim, efficient and not to expensive. Every mans dream !!

Last thing is the flooring. engineered has got to be the way forward under these circumstances.
I take it that this will be glued full length of boards and left floating?
Will 15mm expansion gap be ok ?
Is there an ideal time to leave this flooring to climatise in the house?

 

@matt. He did say general builder. lol

 

i know what current regs are but this property is 300 years old and although at some point someone has given it a refurb and extended it, I’m sure there’s very little that would pass current regs.
I’m not saying that i want to bodge this far from it.

If I’m Doing a garage conversion, the slab Generally has no dpm and no insulation, Building regs permits me to put a dpm down then 100mm celetex or equivalent on top and then lay a floating T & G chipboard floor.

I’m talking about doing a similar thing , sealing the damaged slab once the old floor has come up with pva then using a self leveling screed adding 5 - 6 mm just to flatten it out, then dpm then insulation. I thought there maybe something out there that you guys use in this situation of an old property and not being able to bump the floor up 100mm plus.
Would 50mm or 25mm celotex be ok and not have any adverse affect to the engineered wood floor.
If 25mm say doesn’t affect the flooring then surely thats got to be better than none at all as it is now.

 

building regs says 100mm then you have to use that not 50mm or 25mm...

Or did I read that wrongly

 

.....

 

Many thank for your advise.

Would you have any thoughts on underlay or insulation, for above slab thats not 100mm or is that a silly question !!!!
I can see the oak coming up and a carpet going down , and that'll have no insulation under it at all.
I've used different types of insulations in the past for different jobs that have had a better value for a smaller thickness But these have been foil and bubble wrap or foil and fleece, I did hear of one the other day that was denser than celotex which was half the thickness for the same values, I'm guessing though that these may not be fit for purpose as non of the other guys that have commented have mentioned any alternatives