We have cavity walls yet the house is still very cold…. Thinking about internal insulation..

[bobbyb]

Hey all, looking for some advice.

 

we own a 80s bungalow that has been over the years (not by us) it had extended in a number of ways. We have cavity walling and I believe it is filled with something. We have a range of filled holes in the mortar work around the house.

 

yet sadly the house is still very cold through the winter and getting the house (or a room) up to temp takes ages and costs a small fortune.

 

so I’m now looking for options and ideas as to what I can do about it. 
 

My current thinking is to tackle each room separately and install some PIR to the walls and plasterboard over the top (finish with tape/jointing which I have some experience with) but I’m curious to know what problems this might cause, I realise most people use internal PIR with solid walls. I’d love to know if there’s a reason why I can’t use it or shouldn’t use it here.

 

btw. One small benefit of having a bungalow is the rooms are all quite large, so loosing space around the outside is not the end of the world in most of the rooms.
 

Any thoughts and advice would be appreciated 

 

 

[Conor]

In a bungalow you have a disproportionate amount of heat loss through the roof. What's your loft insulation situation? 

[jayc89]

I'd do some investigative work first.

 

Are all the cavities filled with insulation? If so, what kind? Is the insulation dry or wet?

 

On a windy day, or build yourself a DIY blower (from a car battery and fan), go around room by room and check for any draughts. Our house used to leak like a sieve and it was our biggest contributor to always feeling cold. 

[torre]

Getting a heat loss survey might be worthwhile, see where the heat is going.

 

Have you weighed up internal versus external? External may initially look more expensive but
internal is very disruptive, even room at a time. What would your plans be for handling kitchen and bathrooms? Refitting those will be a big added cost.

 

Both are an (expensive) opportunity to refresh - maybe add a more modern look externally, or a good time to rewire etc internally.

 

We've done internal but only fully renovating an old solid wall property, I'd lean towards external on an 80s bungalow - better insulation, less condensation risk, less disruption, but probably more ££ and less DIY friendly

[Marvin]

Hi @bobbyb

 

Is your bungalow a timber frame with brick/block external wall?  Is your location very exposed to driving rain? Are the external walls painted?

and as @Conor asks have you got a foot of insulation in your loft?

[IGP]

In addition to the loft insulation question, what’s the floor make up is it concrete or suspended timber?

 

 

[bobbyb]

On 26/08/2024 at 06:05, Conor said:

In a bungalow you have a disproportionate amount of heat loss through the roof. What's your loft insulation situation? 

we have around 1ft or so in the loft. I can easily add more if needed

 

On 26/08/2024 at 08:10, jayc89 said:

I'd do some investigative work first.

 

Are all the cavities filled with insulation? If so, what kind? Is the insulation dry or wet?

 

On a windy day, or build yourself a DIY blower (from a car battery and fan), go around room by room and check for any draughts. Our house used to leak like a sieve and it was our biggest contributor to always feeling cold. 

well that's the thing - I have no idea if they gave all been filed, I wasn't even sure this is something you can check?

When you say build a blower - I have a leaf blower. How might you check this? 

 

On 26/08/2024 at 08:21, torre said:

Getting a heat loss survey might be worthwhile, see where the heat is going.

 

Have you weighed up internal versus external? External may initially look more expensive but
internal is very disruptive, even room at a time. What would your plans be for handling kitchen and bathrooms? Refitting those will be a big added cost.

 

Both are an (expensive) opportunity to refresh - maybe add a more modern look externally, or a good time to rewire etc internally.

 

We've done internal but only fully renovating an old solid wall property, I'd lean towards external on an 80s bungalow - better insulation, less condensation risk, less disruption, but probably more ££ and less DIY friendly

i had not considered a heat servay, I didn't know that was really a thing, thank you!

Regarding internal/external. I feel it's a bit of a toss of a coin at the moment. Our house is very dated and there is not one room that doesn't need new carpets or even new windows. and that's one reason why internal clicked with me as its something I know I can do myself. That said - if I'm capable of doing internal I'm probably equally capable of doing external. Something ill need to investigate I think

 

On 26/08/2024 at 08:23, Marvin said:

Hi @bobbyb

 

Is your bungalow a timber frame with brick/block external wall?  Is your location very exposed to driving rain? Are the external walls painted?

and as @Conor asks have you got a foot of insulation in your loft?

I would estimate there about a ft in the loft.  I can always add more. 

and the whole place is brick

 

 

On 26/08/2024 at 08:27, IGP said:

In addition to the loft insulation question, what’s the floor make up is it concrete or suspended timber?

 

 

All concrete 

Edited August 27 by bobbyb

[IGP]

If you’ve got around 1ft in the loft that’s probably fine as long as there’s no obvious gaps in the insulation layer. 
 

Definitely get your cavity walls checked and if they’re unfilled or partially filled, get them filled with EPS beads if possible. 
 

Airtightness is the other large thing that needs resolving, making sure there’s no gaping holes apart from intended ventilation. 
 

Do / get a heat loss survey, there’s a calculator in the forum that’s good or you can use heatpunk online but basically you measure every wall, door, window and assign each element its u-value (how insulating it is) and ventilation losses(blower door test) and it will then tell you your heat loss is at your design temperature (usually -3c outdoor or something, specific for your location). The heat loss results drive everything - cannot stress how important it is to know.

 

Indeed to give an example, one of my close friends considered upgrading a new external door, some other invasive insulation install as they were cold basically. I did the heat loss survey, basically they have tiny tiny radiators that cannot output enough heat even on their gas boiler system at 70c flow temperature. Insulation wasn’t the problem. 
 

I recommend a heat geek, https://www.heatgeek.com if you’re unsure, but if there’s a trusted local heating engineer that’s reputable also go them for a heat loss survey.