Advice sought for Internal Insulation/Plasterboard on solid Victorian Walls

[BobbyMilk]

Hello,

Struggling here. I would really appreciate some advice!

We moved into a Victorian conversion flat late last year. (We are the middle flat of three) Two bedrooms. One of the bedrooms is an outrigger extension. It has three external walls & a small attic space above. Solid external walls. It is also at the back of the building & only gets a tiny bit of sun late in the day.

We quickly noticed that it was colder than the rest of the flat. We’d love to do something about it sooner rather that later, but don’t want to lose to much space (it’s 3.4 x 3.4M) or spend a whole lot (We’re not positive how long we’ll be here.)

I also understand that with solid Victorian brick you can’t just stick plasterboard on to it? I understand that it needs to breathe. (Are there insulated plasterboard panels that can just be attached to the wall with adhesive?) I’ve been reccommended some 12.5mm Vapor Panels, by a decorator but not sure they’re right for Victorian walls.

Also, considering the Wallrock Thermal Lining Wallpaper KV600 as a cheaper alternative, plus some thick carpet & curtains & some more insulation in the attic space.

Happy to spend a little money, but getting many conflicting opinions & really don’t want to cause more trouble with damp/mould.

Thank you!!!

 

[syne]

I spoke to speedline and they stated that their insulated plasterboard was OK to dot and dab on a solid brick victorian house.
Using knauf adhesive and knauf boardsealer for wall paper.
With the caveat that the room be dry, free from damp and that the pointing be in good condition.

It's always a bit of a gamble with this sort of thing because each house is different and suffers/experiences different effects.

We eventually 50mm on following their instructions its noticably warmer already. But only time will tell if it suffers from any problems, there's no guarantees with insulating solid brick...

 

[cdbe]

Have you looked in the loft? Particularly in the eaves where there is often little or no insulation and lots of heat loss. If you have reasonable ceiling height then under boarding with PIR can make a big difference and solves the issue of getting sufficient insulation in the eaves.

More "bang for your bucks"!

 

[BobbyMilk]

Thank you both for this!

I really appreciate it!

Good point about under boarding the ceiling/attic space... I have put new rock woll into the loft and I'm going to add more & hope that helps.

It feels like the three external walls is where the majority of heat is being lost... Don't they say something like 45%... In the old Victorian style, one wall also has a vent high up on the wall.

The pointing outside of the room seems in good shape. We are the second flat up which might help that.

This is the product that the decorator said he would use: https://www.wickes.co.uk/Knauf-Vapour-Panel-Square-Edge---12-5mm-x-1-2m-x-2-4m/p/220230

Potentially a stupid question/comment but here goes.... As I said, I had heard that 'dot and dab' was ill advised on solid brick walls - if the adhesive is applied all over the plasterboard and then the boards stuck to the wall would this be better/safer?

Thanks again... we'll get there!

 

[cdbe]

That has no insulation, so it's pointless. To make a meaningful difference you'll really need 50mm PIR (the type bonded onto plasterboard with built in vapour barrier, and a back face that will stick to the adhesive). You could go thinner but it will take a long time to recover the cost of it. Wickes is not a cheap place to buy insulation boards.

 

[syne]

Yep the foil face will do practically nothing for insulation and very little as a vapor barrier, as how are you going to Tape the foil when it's on the back of the board?

If you were doing it absolutely as best you could you'd battern out about 25mm, then a complete taped air/vapour barrier, then enough insulation (50mm min)to stop the warmth of the room meeting the cold of the solid brick.
You ensure you insulated the window reveals/sill and that plug sockets/lights witches were mounted in shallow boxes that didn't breech through the insulation.
Also you'd ensure when the room wasn't actively being heated that there was enough ventilation for moisture not to accumulate.

And still doing it that way nobody could for sure say if there'd not be problems in five years...

 

[BobbyMilk]

Yep the foil face will do practically nothing for insulation and very little as a vapor barrier, as how are you going to Tape the foil when it's on the back of the board?

If you were doing it absolutely as best you could you'd battern out about 25mm, then a complete taped air/vapour barrier, then enough insulation (50mm min)to stop the warmth of the room meeting the cold of the solid brick.
You ensure you insulated the window reveals/sill and that plug sockets/lights witches were mounted in shallow boxes that didn't breech through the insulation.
Also you'd ensure when the room wasn't actively being heated that there was enough ventilation for moisture not to accumulate.

And still doing it that way nobody could for sure say if there'd not be problems in five years...

Thanks again!

With it being just a two-bed flat and not a huge room, I'm loath to lose much space. Also, to do it properly might be little too much expense when we could well be moving on in 5 years or so... Maybe more the sort of project for a forever home.

I'm tempted to go for the Wallrock Thermal Liner KV600, which I know at 4mm can't have a huge effect, but a cheaper and maybe less risky option in terms of possilbe damp/mould... That alongside, decent carpet, curtains, more loft insulation... potentially a new radiaitor. At present we have a fairly small heater under the window, which isn't the best place for it.

Any experience with the Thermal Liner??

Thanks again...

 

[^woody^]

I understand that it needs to breathe

No. Thats a nonsense repeatedly banded about.

Put insulated plaster board on with the required adhesive and it will be fine.

Or batten and insulate between and over and that will be fine. Leave no voids, and if foil backed insulation board, tape all the joints.

Don't be fooled by the claims of any manufacturer of 2/3/4 mm thick insulation products of any type. I't not a miracle cure, rather its all marketing hype and smoke and mirrors - high price products, low efficiency, minimal effect, and massively long payback times if at all.
And likewise, for endorsements from the Energy Saving Trust - that's no guarantee of the product performance.

 

[StephenStephen]

...or there's this: https://cornishlime.co.uk/products/lime-mortars/cornerstone-insulating-render/

I've not yet tried it, but am seriously considering it...

 

[BobbyMilk]

No. Thats a nonsense repeatedly banded about.

Put insulated plaster board on with the required adhesive and it will be fine.

Or batten and insulate between and over and that will be fine. Leave no voids, and if foil backed insulation board, tape all the joints.

Don't be fooled by the claims of any manufacturer of 2/3/4 mm thick insulation products of any type. I't not a miracle cure, rather its all marketing hype and smoke and mirrors - high price products, low efficiency, minimal effect, and massively long payback times if at all.
And likewise, for endorsements from the Energy Saving Trust - that's no guarantee of the product performance.

Cheers!

You reckon the insulating plasterboard going directly on to the solid brick walls is fine? The pointing on the walls seems fine. Is it, just make sure joints are taped and properly airtight.

Thanks!

 

[kp00110]

I did insulated PB with soudal plasterboard foam worked a treat

50mm pir board /plasterboard from selco and then skim coated and made such a big difference to retaining heat in the rooms

I stripped all rooms back to brick so by the time old plaster came off, only really lost 20mm extra on wall build up as old plaster was terribly thick

Not sure how you can effectively tape the joints with I assume silver tape on the back of the boards but worth trying may be hard and awkward