Plastering single skin wall - How do I prevent damp problems

[glangri2]

I have a 1.6 x 2.2 porch, that I want to plaster the inside of.

The walls are a single skin of brick, and I'm not sure what to do to prevent any damp problems occuring.

I could build an internal wall, so as to generate a cavity, but I don't want to loose that much floor area.

Is there a membrane that I could fix to the wall, so that I could then baton and plaster board the inside face?

Would the membrane need to be breathable?

The walls have a DPC that is lapped into the DPC of the main house walls, and the floor has a DPM that is lapped into the DPC, so I'm not worried about any moisture coming up from below. It is anything that will come through the bricks/mortar than I need to block.

Any advice or suggestions gladly received.....

 

[PrenticeBoyofDerry]

Have you thought about using thermaline boards?

 

[PerryOne]

There is no reason why your porch should have any damp.
In the home damp comes from cooking, washing, breathing, none of these will happen in your porch.
At the worst, when you open the door into your home, the water vapour from the home will spill into the porch, where it will simply pass through the walls to the outside. (If you have a window it may steam up for a while)

 

[ajrobb]

I wonder if there will be high levels of relative humidity in the porch at night. I'd be tempted to treat it like a bathroom and use MR board - just a thought.

 

[glangri2]

....... use MR board

By MR do you mean 'Moisture Resistant' ?

 

[glangri2]

In the home damp comes from cooking, washing, breathing, none of these will happen in your porch.

I hope for survival reasons that I will be breathing in the porch

 

[ajrobb]

MR - yes, moisture resistant board will survive periods of high humidity

A half brick (4") wall will be subject to penetrating damp when it rains but will dry out again. Consider treated battens or galvanised steel frame between wall and lining. Possibly avoid MDF trim. Possibly avoid emulsion paint.

Condensation could be a problem if you seal the porch to the outside better than you seal it to the house. So keep the porch well ventilated. Don't hang coats or otherwise block air movement to exterior walls, otherwise mould could be a problem.

 

[Richard C]

I would not advise MR boards where there is a risk of damp penetration from outside. It will withstand moisture better then wallboard but it will get in an awful mess behind there; you should see the state of some of the bathrooms I renovate & that’s due to moisture travelling in the opposite direction; because of the silicones used in the lining paper, you must also prime it if you intend to skim. You really need something with an integral vapour barrier & I would consider using Thermaline Plus, as suggested by PBD;
http://www.britishgypsum.com/produc...es/gyproc_thermal/gyproc_thermaline_plus.aspx

This has an integral vapour barrier to prevent moisture penetration which can be a problem on single skin walls. I’ve also used Duplex (foil back) boards screwed directly to the walls (you can’t dot & dab it) very successfully where a window in an adjacent wall meant there was not enough space to batten out or use Thermaline.

Condensation should not be a problem in the porch as long as you don’t store damp clothing in there.

 

[Micilin]

Boards will be better for insulation,

but for damp proofing, 4:1 (fine sharo washed ) sand and cement render with waterproofer (no lime, no plas - use as spec on container) and you will never have to worry about damp.

 

[LMuschialli]

Yes there is a membrane that would fix your problem very easily. The product is known as Newtonite which is a 3mm dimpled hdpe membrane which you would mechanically fix to the internal face of the single skin block. This creates a small cavity allowing any dampness to vent behind and a meshed face which can be a key to apply plasterboard on dabbs or if you like a wet finish. I would go for dot and dab. This technique acts also as a dpc as well and any contaminents or salts or staining are dealt with.

Easy fix

Hope that helps

Warren Muschialli

 

[Richard C]

Oh god they never miss an oportunity do they

 

[trowelmonkey1]

Oh god they never miss an oportunity do they

 

[glangri2]

............which is a 3mm dimpled hdpe membrane .............

hdpe = High-density polyethylene

.............Which is obviously not breathable, and so that answers one my original questions.

Having just looked up the price of Newtonite, I am now thinking that a sheet of DPM would give me what I need, then insulate and plaster board on top of it !