House Internal Concrete Floor Integrity No DPM - Cowboy Job

[BeefCube]

My partner and I have just bought our first home.A 1950's bungalow which is need of refurbishment. So far it has thrown us a ton of surprises! The worst so far being the floor in one of the bedrooms. After pulling up the old floor boards we found a concrete poured floor underneath with broken bitumen on it. The concrete has gaps of about 4 inches between it. These concrete "slabs" are separated by very rotten wood. On closer inspection the concrete is only about 3-4 inches thick with soil directly under that.No DPM!The depth of the gaps is roughly 10 inches. The DPC in the walls seems to be intact.

I think the floor used to be a suspended timber floor but the previous owner decided to pour concrete under the floor boards and between the joists maybe using them to level the concrete and just left them there to eventually sponge up any moisture and rot away.

However, as it stands the concrete feels and seems dry. Possibly because the house is in an elevated position.

I know the best solution would be to dig up existing concrete, dig further down maybe 30 inches then put down insulation board , followed by a DPM and then pour concrete. Unfortunately we don't have the budget to do this.

As a cheaper alternative I have thought about filling the gaps with concrete, then applying an epoxy solution all over the floor, then floating a wooden floor on top of this. However i'm not to sure how to do the concrete mix for this, how much aggregate is required etc.


Below are some images of the floor. I have dug out the rotten timbers.

Concrete Floor

• BeefCube
• 5 Jan 2015
• 1

Gap Width

• BeefCube
• 5 Jan 2015
• 1

Slab / Gap Depth

• BeefCube
• 5 Jan 2015
• 1

Slab / Gap Depth 2

• BeefCube
• 5 Jan 2015
• 1

Any thoughts or recommendations besides the expensive approach would be appreciated.

I may follow the sticky posted here:
//www.diynot.com/forums/viewtopic.php?t=80131
Just not sure if i can get the f-ball products in Jersey CI. I'm also unsure of how to fill the gaps.

Thanks

 

[baileysufc]

Before you do anything id stick a decent moisture meter onit to see if it is worth repairing

 

[BeefCube]

Before you do anything id stick a decent moisture meter on it to see if it is worth repairing

Yep the concrete feels dry but after reading the sticky mentioned in my post I'm looking to buy one now .

 

[BeefCube]

Should I go for a pin less one a concrete floor?

I don't really want to spend to much on one, max budget around £70

Thanks

 

[BeefCube]

Can someone recommend a hygrometer flooring meter that doesn't cost to much to test a concrete floor for % relative humidity?

Thanks

 

[baileysufc]

I carnt personal recomend one but imsure if you ring rou d a few companys they wud come and check it for a nominal fee or part of a quote

 

[ree]

Given what you propose then moisture meters or hygrometers are not necessary - and in untrained hands they can cause difficulties and expense.

Clear all wood debris from the slots, and spray the slots with fungicide.

Fill with a mix of very approx. 1 cement: 2 sand: 3 to 4 stone after slurrying the edge/walls of the slots with a mix of 1 sand and 1 cement.

If the concrete surface is smooth then apply a chemical membrane according to Mfr's Inst's. You might need to prime the concrete surface first.

What you do next will depend on what you intend as the finished floor?

The wall plaster should be cut back above the DPC line.

The RH inside wall corner in pic 1. has condensation issues.

Note: if it was originally a suspended floor then redundant air bricks should be visible outside.

 

[BeefCube]

Thanks for that, wasn't to sure on the concrete mix so that helped a great deal.

This is my final approach:

1 - Fill slots with a mix of very approx. 1 cement: 2 sand: 3 to 4 stone after slurrying the edge/walls of the slots with a mix of 1 sand and 1 cement.

2 - Apply bonding compound to concrete

3 - Apply 2 coats of tanking slurry from these guys.
http://www.kabuildingproducts.co.uk/page_2350337.html
This will meet the DPC in the walls

4 - Lay 3 in 1 DPM/Insulating/Sticky Back underlay for wood floors.
Last item on this page http://www.elkaflooring.com/index.php/elka-extras/elka-extras-prepare. This will basically create a floating wood floor.

5 - Lay solid wood flooring

With regards to the RH inside wall corner in pic 1.condensation issues.
This part of the wall was completely boxed in with cables. So i put down to the wall not being able to "breath". What are your thoughts on applying thermal composite board internally to this external wall?

Also the RH slot near the external wall I was thinking of putting down a sheet of DPM against the external wall before pouring concrete in the slot.
Do you think this is unnecessary?

Appreciate your help on this

 

[ree]

Call Kingspan etc. for up to date info ref insulating internal wall surfaces.
Given a 1950's house you will have a cavity - is it insulated?
Is the exterior rendered?

No need for a length of plastic but it wont do any harm - cut it short of the in-situ DPC if used.

What about the other rooms, are they similar, or are they traditional suspended or solid floors?

 

[BeefCube]

Rather than Kingspan I was thinking of a 27 mm plaster board with thermal backing dot and dabbed on the wall.

I think the walls are solid block cavity and there is external render. Should I just leave the thermal board as there is no cavity?

The other rooms from a small inspection seem have a similar floor, concrete with rotten wood between.

From what I can see only the lounge has a ventilation block which I think is blocked now.

Thanks
Dave

 

[ree]

Are you saying that there's no cavity?

Kingspan make insulated plaster board. I should give them a call.

You can attempt to live with the other floors or go in for extensive remedial measures in the sense of doing what you are now doing to one room? The rot wont get better or go away.

Do you have any other damp or condensation issues on the walls or chimney breasts? Back of the hand against the wall surface is a good damp detector.

Any strange smells such as a mushroom smell?

 

[BeefCube]

Yes, no cavity exists, single block construction.

I plan on doing what is done in this room to all rooms. I have to do one room at a time as i'm living there. Should be a pro by the end of it

There is strange mushroom smell indeed, probably due to the rotten timbers

 

[ree]

All skirtings must be removed and any wood contact with the floor should be carefully examined for fungus or fungal strands.

If the kitchen cabinets are still in-situ then check below and behind them.

Look under the bath and any boxed in pipework.

Have the chimney swept.

 

[matthubert]

BeefCube, I think you are right this one is the perfect solution to fill this concrete slabs gap. Just let us know the outcome once you finish the task. Hope you will be successful.

 

[IJWS15]

For the floor try taping a large piece of plastic or cling film over an area of the concrete and see if condensation appears underneath it after a day or so - if it does you have a problem.