Solid wall house (no cavity) insulation questions

[Deep]

Hey all,

I bought a house that is solid wall without a lick of insulation anywhere; no cavity, no loft, nothing. I feel sorry for the whole dear who lived her before.

The house needs some major renovation so obviously this will be one of the biggest things that'll need to be fixed. I was previously going to get EWI but upon speaking to folk it doesn't seem all that and internal will be cheaper and just as effective.

1. My living room and bedroom above have two external walls with one of the walls having a very large window. I was looking at Kingspan Kooltherm K118 insulation but I want to get two thicknesses, 92.5mm on the main wall and 52.5mm on the window wall. Would I run into any issues regarding this?
2. I have a wooden suspended floor with zero insulation under it, what insulation is best to put under it to stop drafts etc
3. I would like to get underfloor heating but I'm not sure how effective it is with having suspended floor. Would I need to put the insulation underneath, then perhaps put screed or something over the floorboards and then put the underfloor heating. It will raise my floor by a fair amount but if it works then I'm not too fussed as my ceilings are 2.6m high.

Any advice will be great!
Cheers!

 

[PlacidCasual]

I looked at this for a stone wall house we own. The big concern in the long run is cold bridging and condensation. Part of the structure connected tot he outer structure will allow heat out but also the tend to be the locations where humidity will escape and then condense on the colder areas. The bigger long term risk is rot of you load bearing trusses etc.

Underfloor heating ideally wants a large degree of subsurface insulation with a concrete raft on top and then your'e underfloor heating in the screed. Effectively you'd need to remove the suspended floor to achieve it. A colleague looked at this but once they started digging down they relaised the footings for the walls were'n't as deep as the desired depth for insulation and it was put in the far too risk category. Depending on the age and construction of the house I'd be wary.

I don't know a great deal about external wall insulation but from a property integrity perspective is seems lower risk, happy to be corrected.

 

[Deep]

I looked at this for a stone wall house we own. The big concern in the long run is cold bridging and condensation. Part of the structure connected tot he outer structure will allow heat out but also the tend to be the locations where humidity will escape and then condense on the colder areas. The bigger long term risk is rot of you load bearing trusses etc.

Underfloor heating ideally wants a large degree of subsurface insulation with a concrete raft on top and then your'e underfloor heating in the screed. Effectively you'd need to remove the suspended floor to achieve it. A colleague looked at this but once they started digging down they relaised the footings for the walls were'n't as deep as the desired depth for insulation and it was put in the far too risk category. Depending on the age and construction of the house I'd be wary.

I don't know a great deal about external wall insulation but from a property integrity perspective is seems lower risk, happy to be corrected.

I wonder if rendering the outside might alleviate potential damp issues coming from the outside, but I suppose I'm not anywhere that will be subject to harsh conditions. I'm in Surrey!

 

[PlacidCasual]

The issue isn't from the outside it's internal humidity tracking outwards and condensing. I'm not an expert but personally the research I've done suggests it's not something to undertake lightly.

When I looked into it many of the heritage associations were suggesting permeable/breathable insulations to alleviate the condensation issue. But I wasn't confident enough to commit.

On the risk versus benefit I put it in the beware box and installed a wood burner instead.

 

[Doobedoo]

Perhaps you might want to have a look at some Wallrock KV600 thermal liner.

https://www.thegreenage.co.uk/the-ultimate-guide-to-wallrock-thermal-liner/

 

[Teknobry]

If it's an older solid wall house, be very very careful of rendering and insulation!

These kind of properties are designed to breathe and putting render on the outside stops the airflow and ends up trapping moisture behind it causing all sorts of damp issues.

Please read this site front to back first before deciding on anything:
https://www.heritage-house.org/

 

[eviled]

EWI is better for old houses in general as the structure of the house still heats, so long as you have some mechanical ventilation (preferably with heat recovery) to get rid of humidity.

IWI is fine if done properly. All damp issues must be fixed at source rather than trapped with render/ damp courses/ mystery products.
I’ve done 2 IWI methods with no issues - bonding insulated board onto brick with pink foam and building a separate stud wall with a 20mm cavity.

Underfloor heating can be done on a suspended floor but gets very expensive due to its technicality and the runs have to be imbedded in a lot of insulation in between the joists.
I went for 220mm rockwool wedged in-between the joist and then draught proofed the boards with draughtX