DIY Internal Solid Wall Insulation

Mankysteve

prosaver wrote: »

Sempatap pictures are untrue

Visual Image Before Thermal After Thermal
have a look at next doors house (on the left) its letting the heat out also ....and when the original house gets insulated ...by magic next door stops letting heat out ...........scam
:rotfl: :rotfl: :rotfl:

Could be a double property turned into a single. What really gives away is the doors and windows. Unless they applying the insulation to them as well. :beer:

dkmax_2

jkgray wrote: »

Now heading into my 3rd winter in my cold victorian house decided that it was time to internally insulate the solid walls. (external insulation is a non-starter as we're in a conservation area)

An option that I'm looking at is Kingspan/Celotex (with integral vapour barrier) applied direct to wall (50mm), through fix with battens (25mm), then Fermacell (10mm) on to battens. Very thick but it leaves an air-gap for services, Fermacell will hold shelves etc. and gets you a U value in the region of 0.35 or better depending on wall type & thickness.

There's also Retrophix which is 10mm Fermacell with a 40+mm phenolic foam layer pre-applied, seems to shave off about 10mm based on similar U values. Not so sure about how services will sit with that as they'll bridge through the foam.

David_Aldred

Hi jkgray,
If you are insulating a solid external wall internally a couple of points perhaps considering are that you need to be really careful to ensure the vapour barrier is fully effective including any service penetrations and junctions because if you don't and warm moist air from rooms gets into the cold side of the system it will likely condense out and cause no end of problems especially if you have timber that could decay within it (always used pre-treated if you are opting for such), in addition to trickling out at the floor / wall junction if severe enough.

Sometimes venting externally on the cold side of the system is required to assist with condensate issues. Intersecting walls need careful design / consideration re: cold bridging and it is always best to do full wall lengths / heights rather than abut existing plaster.

Penetrating dampness getting behind the system is also sometimes an issue which may not just be due to external defects but things such as exposure etc. Incorporating small dimple cavity drainage membranes such as Oldroyd (see Safeguard www.safeguardeurope.com), Platon, Delta etc can be helpful. As Johnjohn indicates if you can keep the pores within the wall itself filled with air instead of moisture this helps on the insulation side of things as obviously water is a better thermal conductor than air. Hope this helps, Kindest regards, David Aldred Independent damp and timber surveyor

jkgray

Johnjohn wrote: »

From a technical perspective external insulation is usually the best option because you can get high insulation values and you don't get problems with cold bridging. ....

Thanks but

jkgray wrote: »

...(external insulation is a non-starter as we're in a conservation area) ...