Worth putting insulated plasterboard behind wall of wardrobes?

[SJRSJR]

Hello

I'm about to tackle a bedroom which is back to bare brick and timber. Two external walls are brick cavity (one has a large window) and the two internal are timber frames.

I was thinking about dot and dabbing insulated plasterboard on the external walls but along the entire length of one of them will be wardrobes. (Not bespoke fitted but they will be pretty much floor-to-ceiling and wall-to-wall.) Would it be a waste of money on that wall? Thanks

 

[ree]

OP,
Why not post pics of the masonry walls, & the stud partitions? Plus pics of the external surfaces?
Is there a chimney breast involved?
Without seeing the layout of the room(s) my experienced advice would be: Dont set any kind of wardrobes against an exterior wall.
If you must use, say, a freestanding wardrobe or dressing table then allow for a clear, well ventilated space behind the furniture.

 

[yorksbuilder]

Not a waste of money. You will not regret doing it now while you have the chance.
My last house had the same situation with normal plaster and we had mould. New house we did the insulated plasterboard and no issues

 

[Rodders53]

Space the wardrobe backs off the external walls to give an air space and some ventilation with some battens.

Victorian end terrace, possibly solid brick, ruined clothes in very short time when I fitted flat pack wardrobes to them without. Once spaced off no issues.

 

[SJRSJR]

Thanks for the replies.

Space the wardrobe backs off the external walls to give an air space and some ventilation with some battens.

You mean battens on the surface to ensure adequate spacing for airflow?

Why not post pics of the masonry walls, & the stud partitions? Plus pics of the external surfaces?
Is there a chimney breast involved?

A couple of photos below, I can get more later. The door is just out of shot on the left. 'Aesthetically' that wall is where I'd like the wardrobes to go, anywhere else and the door will limit the available space and overall aspect. However I do want to avoid a damp problem down the line and will do whatever's needed.

1920s built, cavity, chimney breast on the external wall which is rendered. As you can see there's been a fireplace at some point, that's a hard render over the area, no airbrick. Below, in the living toom, a fireplace has also been removed, there's an airbrick there. There's never been a problem with damp in either of the rooms.

So I'm hoping you'll agree with the other posters that insulated plasterboard and sufficient airflow will suffice! Thanks

PS I also plan to bond it first as the mortar isn't great.

 

[ree]

OP,
Thanks for the exterior pic - however, it wont expand for me. So I cant see the state of the render.
You have two blocked off fireplaces; which means you have two separate flues - if you think its worth it then why not take this opportunity to open the blocking enough for a chimney sweep to sweep both flues?
Its best to vent redundant flues with Hit&Miss vents not airbricks.

If I understand you then on the face of it, you only have to render (only use render dont use any gypsum) the chimney breast wall and the window wall - you could also come in say 1m on the door wall?
Render is a great barrier against penetrating damp but you would still need to keep cabinetwork from contact with an outside wall, & provide a means of airflow under, behind & across the top of units if they go on the outside walls.

.

 

[SJRSJR]

Thanks Ree - the original photo was too big to upload so I had to compress it. Same with the attached, but I've used less compression.

Yes, only two walls are brick so are you saying rather than use insulating plasterboard I should render first then plaster?

How much should the wardrobes come out from the wall to ensure enough airflow? I could also put cupboard vents in the sides and backs but how do you provide airflow below the wardrobes? The base of each plinth is quite narrow and vents will probably look a bit unsightly.

 

[ree]

OP,
The freshly painted gable render in the pic looks OK.
No, just D&D the insulated p/b onto the brickwork.
The general idea is to provide an air flow behind the units. A convection air flow works best but you could leave out the base venting & see how you go on?
100mm should be enough off the wall.

 

[Koolpc]

Def put insulated PB there. It will stop condensation and mould behind the wardrobes as the wall will have a warmer surface.

 

[mrrusty]

what @Koolpc says. If you have a ventilated cavity, then insulated PB on all external walls is the way to go. Thickest you can accommodate. You won't need much airspace behind your wardrobes with thick insulated PB.

You won't need to do anything to the bare brick but do remove the bulk of the dust. Insulated PB can be installed directly on to the brick with standard dab adhesive. If using thick insulated PB make sure your sparky knows because he'll need to leave long enough tails at the socket positions when he does first fix.

 

[SJRSJR]

Thank you all, that’s really helpful to me and also anyone else thinking about it.

One last question - I see the insulated board can be with or without a vapour barrier. Should it be with? Thanks

 

[SJRSJR]

Another last question!

If you have a ventilated cavity, then insulated PB on all external walls is the way to go,

There’s an air brick in the exterior wall which I presume means it’s ventilated. What if it wasn’t?

 

[mrrusty]

Yes, use insulated PB with a VCL. The reason being you want to prevent as much room air as possible reaching the now-colder brick behind it because the room air will probably condense. Assuming at least some interstitial condensation occurs (i.e. condensation inside the fabric of the wall), then this is why a ventilated cavity is important because the ventilation provides a mechanism to evaporate any condensation which would otherwise be trapped inside the wall behind the render.

This is very much like how a modern timber frame house is built. From inside to out you'll have plasterboard, VCL, insulation with structural timber frame, (OSB), breathable membrane, ventilated cavity, external decorative waterproof cladding/brick skin. The ventilated cavity is essential to evaporate any condensation behind the outer skin of the building.

 

[SJRSJR]

Thanks for the explanation, mrrusty, helps me understand why.