Renovation - External Insulation & new windows?

I've just put in new triple glazed windows and external wall insulation (EWI) on my house. It's a big house and cost more than 20k and depending on the size of the house it will probably cost you more than 20k too.

I think you're better to insulate the house than carry out cosmetic work. If you were to spend the money on say a kitchen and bathroom refurb then by the time you sell it you'll have a kitchen that's 5-10 years old. The way things are changing so fast it could be seen by new buyers as an old fashioned kitchen. I know we'd like to think a kitchen would last more than 5-10 years but from a selling point it would be a nice kitchen not a brand new state of the art one.

Doing EWI and new windows are the better bet here and you can currently get grants to help you. A few tips. Have the new windows positioned so they're moved out in line with the new EWI as this will create a fully insulated fabric. If the windows stay where they are and you externally insulate you'll have cold areas around the window reveals. You'll need to carry out both at the same time to achieve this so you can't eg. do windows this year and EWI next year.
The next point is to get the most from the EWI you'll have to pump any external wall cavity you have. This is to stop cold air currents going around the EWI in the wall cavity. This in comparison is relatively cheap and will improve the house further. I'd also get 150mm of insulation or 200mm although most of the companies installing it will probably just offer you 100mm as this is what they do daily to comply with the grant. It's not much more expensive as the labour is the same, it's the same amount of plastering, etc. but provides a far warmer house. You can also do stuff like remove the roof soffit to allow the EWI continue up to meet the insulation in the attic and remove the cold bridge in at the eaves. If doing it once do it right as it's hard and costly to go back later and fix it.

If your timescale is a number of 3 or 5 years...frankly you'll never see the payback in running costs, nor the commensurate value in a sale situation for EWI. 
Not too many viewers of house would notice it, and I'm not sure they would attach the appropriate premium to it (running costs are far down the importance list for people looking for a home - things like floor space, layout, commute distance, shops nearby, schools, aspect even all come before the bimonthly bill)

What I would suggest, and bearing in mind your OP where you note that the house overheats alot, is look at the heating controls, as a low hanging fruit. If you were to optimise the heat input to the house (e.g. fitting Thermostatic Rad Valve and a decent programmer/temp sensor) you would be able to more easily maintain a comfortable temperature, notwithstanding the heat loss at present.

Even if you were to fit EWI down the road, you would need decent controls anyhow, to prevent an overheat situation. This is a screenshot from the Nest programmer in my home for the past few days, which has EWI - you'll still need to input heat, so you may as well control it correctly:


Windows are probably a good idea if the old ones are poor. Doors too - the composite ones give good u-values. And altogether you could probably address some airtight issues along the way with installing those elements? A buyer might notice & appreciate details like that. And a BER at the time would bear in mind those types of upgrades, and read well to buyers

OP:
1: I would max the mortgage and conserve cash, keep some in reserve and do out a repayment profile based on increased interest rates.
2: if this is a refurb and flip then you should have verifiable work and keep a record of your energy bills now and afterwards.
Hoping to regain your investment based on a BER differential is cuckoo land, it will need one for you to buy anyway and its based on expected occupancy rather than actual.

The overheating may be due to poor heating controls in winter or in summer due to solar gain through windows and roof/velus windows, with little attic insulation so check the need for perhaps summer shading of south and west facing windows, especially second floor.

Would I do it, yes, if you have the cash/debt and enjoy the improved living conditions

If you're wall is cavity block that would count against EWI

I would also consider internal wall insulation especially if house needs or you are considering some internal refurb work

I have experience of both Internal (my last house) and external (current house)..
While the houses are very different, and there are other factors at play I found internal very effective

The jury is still out on the External.

I would also guess you're more likely to get your money back if selling in a few years by spending money on internal + heating improvements + extra refurb rather that just external

little_monty wrote: »

If you're wall is cavity block that would count against EWI

Why?

I accept that EWI is superior .. and I don't regret getting the EWI installed ..
It's just that I have not fully convinced myself that in my case its benefits justify its cost.

I didnt get one (how many people retrofitting EWI get one ?)
I have good attic insulation, good windows , dcv and i don't believe there is a excessive problem with draughts in my house.

One thing i notice is the 2 bedrooms with 1 external wall are stay warmer for much longer than 2 bedrooms at (south) gable end of house with 2 external walls (and rooms are very similar otherwise) .
While I know this is to be expected to some degree I see this as indication alot of heat is being lost to external walls