Cavity wall insulation thoughts

quattros

Hi all I am thinking of getting cavity wall insulation I had a inspection done a while back and there is a a cavity present on the house  , I have heard mixed reviews about cavity wall insulation, Have people had it done and then regretted it ? And suffered damp issues etc?

Jeepers_Creepers

Of the three - external insulation, cavity insulation and internal insulation (I've seen your other thread) - the latter is by far the best overall.

Guaranteed results and no real drawbacks - apart from a slight loss of internal space.

FreeBear

Jeepers_Creepers said: [internal insulation] Guaranteed results and no real drawbacks - apart from a slight loss of internal space.

Downside of internal wall insulation - If you have sockets/switches on the exterior walls, these need to be repositioned. Any radiators may need battens to spread the weight and the plumbing adjusted to suit. You also need to give some thought to stuff like curtain rails if you are hanging heavy curtains..

Internal wall insulation in kitchens - Better off using battens infilled with rigid insulation boards topped off with thick ply wood rather than plasterboard - This will give you a solid surface to hang wall units from as long as substantial fixings have been used for the battens.

EssexExile

We had cavity wall insulation put in our 1950 house about 20 years ago, no problems so far.

DevilDamo

External insulation can also cause issues with existing window/door cills, etc... In the majority of situations, it’ll require Planning and BR’s. Anything you can do within the cavity and internally would save these issues.

twopenny

Had cavity wall insulation and the upside was that the house was warmer when the central heating was on as I wasn't heating the walls.

The downside was that - as  I had a south facing house that would warm up with the sun spring and autumn so I didn't have to use the heating till late in the year - the sun no longer warmed through to the inside. I had to have the central heating on for more of the year so not saving money.

The cold without heating was noticably different.

It also tended to trap the heat during heat waves.

There was initially a little damp as the house adjusted but it dried out without any problems.

Davesnave

We have cavity wall insulation and live in an exposed spot. While I'd not have wanted it myself, due to tales of woe elsewhere, there are no problems whatever, so I'd guess it was installed correctly.

Most problems with CWI are  due to poor installation, or maybe a bad build in the first place as well.

Jeepers_Creepers

FreeBear said:

Downside of internal wall insulation - If you have sockets/switches on the exterior walls, these need to be repositioned.

Ooh, never thought of that - they would be cold spots.

I guess if 2" insulation were used, you could sink the boxes into the top 1" so still have a layer behind, but good point.

travis-powers

The trouble I had was because my roofing felt was non breathable I had terrible condensation in my loft space!
 I solved the problem by putting small pieces of 2x1 in between the layers to improve air flow.

m0t

DevilDamo said:

External insulation can also cause issues with existing window/door cills, etc... In the majority of situations, it’ll require Planning and BR’s. Anything you can do within the cavity and internally would save these issues.

EWI s permitted development unless it changes the external appearance of the building (beyond just making it thicker).

When I had mine done our Council just sent me an email telling me I was good to proceed.

Barsnog

There are a lot of claims on Cavity Wall insulation. In my experience there is nothing wrong with the CWI, it is the property is not properly ventilated. Installing CWI is akin to putting a quilt over your head. The air gets moist due to cooking, showers and breathing, etc. There needs to be proper ventilation. However, in December the last thing you want to do is open your windows for a few hours to ventilate your property!