There is a project ongoing in the area whereby houses are having external insulation put on for free. Some sort of government scheme run by E.On, but obviously subcontractors doing the work.

Our house is brick with roughcast, and a few years ago and at significant expense I had the cavity wall insulation, which had been done poorly via a similar free scheme when the previous owner lived here, removed as it was causing bad damp in the house. Since its removal the damp has gone. Obviously I appreciate the differences between CWI and external, but this previous experience and expense makes me quite cautious.

Here they seem to be putting on thick grey foam panels, topped with two layers of render, the top one being coloured and roughcast. They are also putting white PVC windowsills on, and the same along the tops of the insulation tucked under the roof edge. They fix your drainpipes, Sky dish etc. back onto this new stuff. With it being free I am assuming each house is done as cheaply as possible, not that I want to criticise the contractors, but you know….

The houses here do take a bit of a battering from the weather, being on the west coast of Scotland.

I know a few people going for it, and a few who aren’t because they are concerned about future problems, the render being fragile, cracking easily and being hard to repair, the strength of the stuff for fixing drainpipes etc onto it, various things. I am struggling to decide whether to go for it or not so any thoughts or experience would be appreciated.

Do you know who the manufacturer of the system is? Some are better than others. The Solix system is pretty robust and can take a battering before being damaged

No, not at the moment, but I’ll see if I can spot it at someone’s house.

Pros:
Your house will be toasty warm in the winter and cooler in the rare hot days of summer.
Your energy bills will be substantially lower with the increased thermal resistance of the walls.
If done to a decent standard it will make your house look shiny and new.

Cons:

Thin coat acrylic insulated render systems can be susceptible to mechanical impact damage when kids kick footballs, hitting them with bins, propping ladders against the wall, etc. If it gets damaged and needs to be patched it will always be visible unless you recoat an entire elevation. Some systems can be reinforced at ground level to reduce this.

Given that you’re increasing the thickness of the external wall by more than 100mm then this will likely require alterations to the roofline. Fascia and soffits and guttering / downpipes may need altering.

The aluminium or PVC overcills can sound like the drummers at the Edinburgh tattoo when it rains if they are not fitted with sound deadening tape.

There is a load of disruption when the works are taking place. Scaffold / mess in the garden / inconvenience.

I’ve been directly involved in (literally) about a million square metres of this over the past 10 years including most of the high rise tower blocks in Glasgow.

Would I pay to have it done on my house? Yes. (but unfortunately the construction of my house precludes it.)

edit: For clarity, I’m not currently involved in installing this anywhere, so not trying to make a sale 🙂

Thanks very much. Suppose there is a bit of damage, is it easily fixed by any competent builder – point taken re the colouring but I could probably live with that for a while. If there is a crack and water gets in, where does it go, does it damage the insulation or just make its way down and out the bottom.

Lastly, can you paint onto it?

If we qualify (not 100% sure we will as it is meant to be for cavity-less houses, but given the previous problems we had with CWI I’m going to see if we also qualify) this will be free.

Suppose there is a bit of damage, is it easily fixed by any competent builder

Yes, assuming they use the same materials

If there is a crack and water gets in, where does it go, does it damage the insulation

The grey foam insulation is probably EPS – expanded polystyrene – the same stuff they make cups out of. intrinsically water resistant. If it’s mineral fibre insulation (rockwool) its usually bound with resin which makes it water resistant.

Lastly, can you paint onto it?

If you use the right paint – depends on the individual system.
Shouldn’t need painting for at least ten years or so, although some systems can be susceptible to algae growing on the system – especially if the finish is white.

Cheers, really appreciate your help. It’s a sandy colour that’s going on most of the houses. I noticed they are putting a vertical strip of rock wool between the grey foam at the boundary of semidetached houses.

That’s an expansion joint to stop any movement of the building cracking the system.

Ok, makes sense

We had our Ewi applied to our house this time last year and it has been all good so far.Our house has no cavity so this was the only real option and was subsidised under the green deal scheme.
There is no painting as you choose the colour you like and this comes ready mixed in the top coat.
As posted above some waste/water pipes have to be moved as the cladding projects 100mm from your existing wall.
Because everything projects 100mm your window reveals are deeper and you do loose a small amount of light but it is not that notiiceable
The house seems to keep its heat longer and along with having a modern boiler fitted our gas bill fallen dramaticlly.

Did whole estate near us, and the high rises in chester, most of my cusomers who had it done say its warmer in winter and quieter from wind noise, and cooler in summer, but if you share a semi with a neighbour who doesnt want it done then your house will be about 4 inches plus deeper.

Also waste and down pipes need to be moved out, and there is some amount of noise as they drill for the anchor fixings, but if its free go for it, it will save you cash in the long run and make the estate uniform in design.

Estate 😯 How very dare you 🙂

Don’t think the neighbours are getting it, they’ve still got CWI in theirs, but there is a drainpipe running right down the boundary line between the two houses so that should half hide the edge.

I like the idea of cooler in the summer, and the ice queen will appreciate the extra warmth during the other 11 months.

How confident are people that it won’t cause damp problems? Not so long ago external cement render was all the rage and it’s been a bit of a disaster for many buildings due to the lack of breathability. I do know of builders who predict that external insulation will be the next disaster for future owners to sort out.

If you insulate and render a house with plastic and silicone materials it doesn’t breathe as well, and the interior becomes more humid, which makes condensation on cold spots worse and can make the general atmosphere in the house fell really horrible. It’s the reason trickle vents exist on modern d double glazing.

How much moisture is in your house is almost completely governed by your life style, but it’s usually good practice to ensure your most humid rooms (kitchen, bathroom and esuites) are vented at the least. If your upper floor ceilings aren’t equipped with a moisture barrier it’s probably a good idea to increase loft space ventilation too.

It’s quite common practice for loft insulation to be up graded at the same time as EWI and cavity insulation and if it’s not done properly loft ventilation is often reduced at the same time as the net loft temperature is reduced from the improved insulation. More condensation in the loft results.

People often have real problems comprehending just how much water condensation can produce in a home, preferring to believe in rising damp and leaky walls an roofs.

Some insulation types are more breathable than others. Always get a condensation risk analysis done. Generally rockwool or similar is more breathable than EPS and whilst most of the acrylic renders and finishes are only 6mm there are lime based renders available if breathability is s concern. Having said that EPS is generally used and works if correctly specified.
The main concern is finding a good installer and attention to good detailing is fundamental. A mineral based system with a dash finish is generally more robust than the thin acrylic types.

I’ll take a draft over damp any day of the week.

There is a street on my commute which is having this done. All bar I believe one house has had it done & it stands out like a sore thumb – I can’t imagine they will have an easy task to sell when they decide to…

There is a street on my commute which is having this done. All bar I believe one house has had it done & it stands out like a sore thumb – I can’t imagine they will have an easy task to sell when they decide to…

They should have no trouble at all if theirs is the only house that doesn’t have mould growing up every window reveal and corner. I think this whole insulation malarkey is overblown. I had ours CWI and it’s been the worst decision ever. Condensation and mould is a major problem now. So what if the bills are lower. It’s an unhealthy environment!

I thought long and hard before getting my place CWI. Glad fibre or blown foam were never going to be on the cards, but graphite coated poly beads specs were pretty good. 2 years in and not a hint of damp, but I installed DG with trickle vents and passive stack ventilation to the bathroom and kitchen the same year.

I still get condensation in the sun room in the wintet, but that’s just glass and poly carbonate. Something is always going to show there.

Would you qualify for that OP?
I thought that external insulation was for solid wall builds.