Damp on a solid exterior wall in Victorian house

[Mr Chibs]

Yes, just go over it, I blocked one up with spare pieces of insulation boards first, then over boarded it.

Yes, you might have to remove the vent to get the board flat.
Mine had been replaced previously... just a crappy flat plastic job.

 

[dontbelieveawordofit]

I haven’t read extensively but....waw. sledgehammer / nut springs to mind.
I wouldn’t contemplate sticking any sort of insulation directly on to old victorian solid walls that show any signs of dampness, and will contain a % of moisture that needs an escape route. your asking for trouble.
as for the vent , you havent said if its venting directly from outside or venting a chimney breast? I wouldnt block that up either. some of the information you have received here is far too general / overly expensive and even innaccurate.

 

[Jupiter01]

you havent said if its venting directly from outside or venting a chimney breast?

It's venting from outside and not a chimney breast.

 

[Jupiter01]

When sticking the Insulation Boards to the wall, do i need to use the foam adhesives or can I use gripfill? I am familiar with the latter and never used the foam stuff.

As per advice, I will also mechanically fix the boards to the wall.

 

[JP_]

I used foam - I think it gives a lot more coverage than gripfill - you spray it on, wait 4 minutes for it to cure a bit, then press onto the wall. If squashes and covers a larger area than a line of gripfill. Also better to foam if the walls are not perfectly flat.

My first insulation + boards have been up about 2 1/2 years now, still solid, still no mould at all. Everything good. But as mentioned, if the walls are damp from the outside, def. use mechanical fixings too. I used a couple on my boards too, just to be on the safe side. But I did a test, sticking a bit of plasterboard to a piece of wood with the everbuild pink foam, and I could not pull it off. Strong stuff.

 

[Jupiter01]

Should the screws be added once the foam has set?

 

[JP_]

I think that would be best - if you screw through unset foam it might stick to the drill bit.

 

[Jupiter01]

You guys have been immensely helpful - as is typical on this forum.

I really appreciate it. Will def post some pics and may be a question or two before that

Have a good day

 

[Jupiter01]

A further question on this please: the insulation board, plasterboard and some gaps in between are likely to given me a distance of around 6cm from the wall. Am I definitely going to be okay to plug and screw through this to hang a double pane radiator? It’s 1200 wide

 

[Mr Chibs]

Are you saying wall, 50mm insulation, 12mm plasterboard (with a few mm of uneven wall?) if so yes you will be fine.

Drill through everything, into masonry, plug and fix as normal, just don’t overtighten fixings. My boiler if fixed like this, and it’s a heavy brute.

You can use coach screws and plugs, or meaty screws depending on size of rad(s)

You’ll be fine.

insulation washers might be the answer if you want to mechanically fit boards to wall as well as using foam.
I wouldn’t use gripfill.

 

[Jupiter01]

UPDATE: made good progress today. Got to use my new laser level for the first time. It was immensely helpful.



I ended up using a bottle of the foam adhesive on a single board! Does the foam seem excessive?

 

[Jupiter01]

Can I use normal screws with flat washers to mechanically fix the insulation boards?

 

[Mr Chibs]

Good job, foam quantity is a little excessive, but I suppose it depends on how wonky the walls are.

Add a couple of fixings to the board as well, and it’s on for good.

Yes, but the insulation washers are concaved, so they don’t break through the boards when you tighten them.

From memory they are around £8 per 100.

It will be warm in there when you’ve finished !

 

[endecotp]

I think I used one can for two boards on a rough wall, so you’ve been a bit over the top but not ridiculous.

Remember that the purpose of the mechanical fixings is to prevent the new wall from falling off in the event of a fire. So you want to screw through both the plasterboard and the insulation into the original wall. Screwing through just the insulation, with insulation washers, is not sufficient.

 

[Jupiter01]

So you want to screw through both the plasterboard and the insulation into the original wall.

I decided not to drew the insulation. I’ve started fitting the boards and will then mechanically fix. This will take care of the plasterboard and the insulation.

Is there any argument for starting the next board on the right of the wall rather than continuing from left to right? I was thinking that I could fit most of a full board on the right side. Am I then creating a problem with trying to adjust the level of the small section I would need to do in the centre...

I’d appreciate any advice on this matter.