Internal wall insulation or not?

AlwaysGotAQuestion

WestonDave wrote: »

Have a look at Marmox boards - you can skim plaster directly onto these so it saves having to put insulation then plaster board then skim - it cuts out the plasterboard layer. They were intended for wet rooms etc but I've seen it used in a lounge to good effect where someone wanted internal insulation without losing as much internal space.

Thanks for this, will take a look. Apologies ofr the delay had issues logging in!

AlwaysGotAQuestion

the_r_sole wrote: »

If you have cwi already you should get someone to do a dew point calculation with the new insulation as you may be in danger of the vapour forming before it gets to a ventilated space (where your cavity used to be)

Going to look at this thank you. Apologies for the delay had issues logging in!

AlwaysGotAQuestion

Ben84 wrote: »

The kitchen and bathroom are probably the two rooms I would be most interested in doing this, on account of it reducing condensation.

Otherwise, I think it's not a bad idea, but may have a very long pay back in money savings. Are you going to be using notably expensive fuel to heat the house? Also, does the existing plaster have to go anyway, because if so we should be comparing the difference over re-plastering?

Apart from in the odd place where we are patching repairs the existing plaster is staying.

We will be using mains gas for the central heating and are having multi fuel burners in two rooms downstairs. We have oversized the new radiators slightly too.

It's the pay back that is my concern. If I thought we could make the money back in a couple of years it would be an easy decision but I think it would be significantly longer.

AlwaysGotAQuestion

Doozergirl wrote: »

I love the stuff. Having lived in houses with and without, I would always take the opportunity when it is available. This house didn't really present the opportunity to us, but I regret it all the time.

That said, your house has a cavity. If the cavity is a sensible width, then that is your cheaper option. Insulated plasterboard is really the option for houses that don't have cavities.

I'd check on what you already have.

We're getting the cavity checked to see if it needs topping up as we have no paperwork for the cwi.

AlwaysGotAQuestion

sniggings wrote: »

have you looked into if the combi will be the best option?

OH has done a lot of research into this and we have taken advice form the plumber on which one would be best. I would love to give you more details but I haven't had much to do with it!

richy999

I think the payback time on the internal wall insulation, considering you already have a double cavity construction already insulated, will be massive.


I would be tempted redirect the funds allocated to this into the most energy-efficient double glazed windows you can lay your hands on. Or as you are putting in a totally new central heating system and have access via the suspended floor, how about an underfloor heating system?

AlwaysGotAQuestion

richy999 wrote: »

I think the payback time on the internal wall insulation, considering you already have a double cavity construction already insulated, will be massive.


I would be tempted redirect the funds allocated to this into the most energy-efficient double glazed windows you can lay your hands on. Or as you are putting in a totally new central heating system and have access via the suspended floor, how about an underfloor heating system?

We are getting all new double glazing. The best we can get. We are also getting the ground floor insulated underneath with spray foam (can't remember the name of it). We debated underfloor heating but we have one concrete floor in the kitchen which we couldn't do and we are worried we would be wasting energy/heat as the void under the rest of the rooms is 5 feet tall so I'm guessing would "absorb" a lot of the heat from the underfloor heating if we had it.

richy999

The under floor heating is usually installed with diffusion plates and insulation beneath to direct the heat upwards and prevent it from being wasted in the crawl space. As you have one concrete floor though it would be a more complex installation (raising the floor level in the kitchen etc).

Is your suspended floor of the timber variety? if so, I would recommend insulating it with Rockwool insulation or something similar.
I considered spray foam when I insulated my suspended timber floor but was worried about the spray foam causing issues with the joists/floorboards as they need to be ventilated. Also, I would not have been able to access the central heating pipes which also run in the floor void without great difficulty... something to consider?

Leon_W

If the cavity wall insulation checks out OK I don't think I'd bother with internal wall insulation, but if you are gutting and redecorating then as a belt and braces job it can only help.


We have a detached solid wall cottage and suffered terribly from condensation and black mould in the bedrooms with the walls running at times. It didn't matter how high I set the heating the rooms always felt cold ! One by one I fitted Celotex (insulation backed) boards (40mm),dot and dab to all external walls in all the bedrooms and bathrooms and then re-plastered.


http://www.celotex.co.uk/applications/wall-insulation/internal-solid-walls


The difference is remarkable. Rooms stay warm and dry and heating is hardly needed, the Rayburn in the kitchen keeps the chill off all on it's own as the heat rising through the house is retained rather than lost. Wish I'd done it years ago !

AlwaysGotAQuestion

richy999 wrote: »

The under floor heating is usually installed with diffusion plates and insulation beneath to direct the heat upwards and prevent it from being wasted in the crawl space. As you have one concrete floor though it would be a more complex installation (raising the floor level in the kitchen etc).

Is your suspended floor of the timber variety? if so, I would recommend insulating it with Rockwool insulation or something similar.
I considered spray foam when I insulated my suspended timber floor but was worried about the spray foam causing issues with the joists/floorboards as they need to be ventilated. Also, I would not have been able to access the central heating pipes which also run in the floor void without great difficulty... something to consider?

Yes, it is a timber floor. We've asked the spray foam installers about the implications of sraying over the heating pipes and are waiting for a response. Will see what they say.....

We have ventilation elsewhere in the house so aren't too worried on that front.