New floor in cottage

[Neddy flanders]

Brick cottage with no cavity in walls suffers from Damp, as they all do.
stripping old plaster off to allow batten and insulated plasterboard to be fitted.

floor appears to be bricks with no mortar laid over a failing lime mortar base of some sort.

If i dig out floor to put in a DPM, insulation and concrete, where should the edges of the dpm go? just laid up side of brickwork? moisture from under floor and lower walls will then rise in walls and escape into void between insulated plasterboard and wall. should these be vented??

 

[teslacoils]

Following this as I'm in the same boat. Really showing it this year.

 

[quavers]

if i remember correctly the battens for the bottom railfor the walls move it inside the dpm so it is always dry , your insulation should have a void between it and the brick wall so you will always have a movement of air behind the insulation to dry things out . good opportunity to fit underfloor heating at this point if you have the floors up .

 

[Nearly]

Dimpled wall plastic sheet against the wall behind the stud wall is how we did our cottage.

 

[zero]

We dug old floor up, covering of sand, builders put visqueen through to a few inches above finished floor level up behind the plaster boards. Then a layer of concrete, insulation, sheet of plastic, underfloor heating pipes, top screed.
Walls are insulated plaster board down the sides and insulated stud walls on the gable ends.
If possible make a few doorways a bit wider to get a micro digger in. It makes life alot easier.

 

[Dry Rot]

Don't forget the overall level of the surrounding water table. Lowering ditches made the greatest significance to the dryness of my house and the critical deepening was about 300m from my door! But it is very flat here. Damp proofing can be injected into rubble walls though reports of effectiveness are variable.

 

[Timbo]

Brick cottage with no cavity in walls suffers from Damp, as they all do.
stripping old plaster off to allow batten and insulated plasterboard to be fitted.

floor appears to be bricks with no mortar laid over a failing lime mortar base of some sort.

If i dig out floor to put in a DPM, insulation and concrete, where should the edges of the dpm go? just laid up side of brickwork? moisture from under floor and lower walls will then rise in walls and escape into void between insulated plasterboard and wall. should these be vented??

Dig floor. Soft sand. Membrane, bring it up the walls to just above skirting height, secure it with battens.. Insulation- at least 4 inches. Use at least 1 inch up the walls to skirting height. 2nd membrane, again up to skirting over covering the insulation. Now you have what looks like an empty paddling pool. Install UFH. Concrete or screed on top to finish height. Trim away excess membrane, install skirtings..

If you miss the 2nd membrane the screed or concrete can get under the insulation and the whole lot will float.

 

[HatsOff]

Your walls shouldn't be damp - that indicates there's a different problem that needs to be solved first. Battening over a wet walls just hides the problem rather than treating the cause of symptom.

Damp is either caused by penetrating water (usually high external ground levels or rain splashback, a pipe leak, defective gutters) or by condensation due to high humidity inside the house (minimal extraction from wetrooms/kitchen combined with modern windows sealing the house up). Treat that as well

Insulation is great but it isn't a cure all.

Draining membranes work but are designed for cellar walls. They are a sledgehammer to crack a nut if you're just trying to treat damp.

 

[Nearly]

Draining membranes work but are designed for cellar walls. They are a sledgehammer to crack a nut if you're just trying to treat damp.

In our case it was converting a cow shed with 9" wide solid brick walls into a house. Only one opportunity to fit a physical barrier so why not use a sledgehammer rather than a toffee hammer?

 

[HatsOff]

In our case it was converting a cow shed with 9" wide solid brick walls into a house. Only one opportunity to fit a physical barrier so why not use a sledgehammer rather than a toffee hammer?

Money? Spenidng it on an unecessary membrane means that you can't spend it on something else. There's a minor risk that the walls become saturated and are more vulnerable to frost damage but I expect by and large it just isn't doing very much.

I always recommended Type C waterproofing (that is, drained membranes) for below ground conditions, but never above. The fix to damp is usually quite simple - an extractor, changing external concrete to gravel so it doesn't splash on the walls, or at worst changing gypsum plaster to lime plaster.

 

[jamesy]

We’ve done up several old stone built properties over the years and dug floor out for ufh, we have always ran the dpm under the floor about a meter up the external walls. These old stone buildings be it houses or steading have no dpc