Intro - Bungalow Retrofit

[Novice Becky]

Hi. Just officially joined so I can ask some questions on this amazing forum!  I'm a novice but I enjoy DIY (when time permits), so far mainly designing and building storage/fitted cupboards/kitchens, working with wood. Never built a wall in my life - but this forum gives me confidence to try things.

 

A LONG introduction to my ongoing retrofit project (lots of questions to follow) ...

 

I'm reattempting a retrofit project that started 15 years ago when we moved in. We're in Surrey (M25 J9) and have a 1960s bungalow:

gable roof detached bungalow

side extension (on the right) built by builders 2009/2010 - Side extension has a double-hip roof.

Approx 134 m2

Front of house is north-facing - so living area is south-facing (with lots of solar gain)

solid concrete floors (suspended concrete floors in extension)

open plan living/kitchen/dining (used to be 3 rooms)

4 bedrooms

snug

study

1 bathroom

1 shower room (kinda also utility with washing m/c)

AIMS:
Reduce our fuel bills and CO2 emissions, heading towards net zero

Stop using fossil fuels so stop using gas.
Resolve our condensation problem - cold and north-facing spots get mouldy. Very high humidity readings in winter.  It's got worse, I think, because 15 years ago we fitted high-spec argon-filled wooden framed double glazing to all but 2 windows, I insulated loft with recycled plastic insulation (laid over old mineral wool) and our children are now all teenagers so bigger lungs and bigger baths/showers. All bedrooms have trickle vents. We also have 1980s CWI which has failed (a surveyor put a camera in the cavity a few years ago).

 

BACKGROUND:
When we moved in (2007) and did a load of work it was hard to find any 'green' trades/expertise and I just had my Green Building Bible. I was told MVHR wasn't appropriate for my leaky house. People were clueless about underfloor heating let alone heat pumps and timber frame building etc. so we just did what we could.  I've put off getting things done/repaired because of a string of situations and I was desperate to have a retrofit assessment first to make sure everything worked together - Whole House Approach.  I've finally found and had a retrofit assessment which was incredibly underwhelming and didn't shed much light (because my home is, on paper, already above average in terms of efficiency measures, despite the fact we consume more than our fair share - approx 22,000 kWh of gas and 5,300 kWh of electricity PA).

 

TO DO LIST:

MVHR (Leti guidelines suggest this is a very good option for ventilation for me) ... so remove and block up 3 external vents/fans

Replace 2 old windows and very leaky front door

CWI - extract mineral wool and replace with EPS beads (waiting for the above to be done first) and the company will also fill the smaller empty cavity that is behind the wooden cladding at the front of the house (Bed 3).

ASHP coming in January (I want to get this done before I have a big repair bill on my 15 year-old gas boiler - or panic replacement)

re-lay loft insulation and insulated boarding after it's been trashed with MVHR and ASHP installations.

 

Then work at making the house more airtight-

• I bought a Flir camera and this highlights some problem areas that need insulating/draughtproofing, particularly around windows.  Windows are high spec wooden-framed windows but fitted by a general builder with no attention to thermal bridging (I've learnt a lot since then). Two at the front were fitted by a FENSA fitter but they're possibly even worse. Also in the extension I can see that the CWI does not reach to the top of the ceiling and we have problems with thermal bridging across the ceilings with two steel joists
• Looking into retrofitting airtightness tape around windows - looks like I have to strip back the plaster. And something like Compriband on the outside. Not sure about sills
• Draughtproof windows/doors, loft hatch plus plumbing that goes through external walls.
• Chimney in lounge is still in situ but not used (currently insulated with a 'chimney sheep')

• Bathroom and shower room both need refurbishing, insulate bathroom ceiling (steel joist)
• Kitchen and bathroom lighting (retrofit LEDs didn't last)
• And building storage for the endless 'stuff' my family accumulate

• External Wall Insulation is very expensive (esp for the smaller gains it would seem to bring) so I'm thinking creatively and may build a wooden lean-to along the side passage (with thick polycarb sheets on roof) for storage and drying washing which would also act as a buffer zone. And I could construct something to act as a buffer zone along the other narrow side of the house.  Maybe some EWI at the front (north).
• Shading at the back (south-facing) - my first attempt at making shade sails out of organic cotton sheets was not very successful!! Back to drawing board on this
• I'd like to replace the loft insulation with something breathable and use a vapour control layer etc but because it's a bungalow there's a large surface area so expensive to do and lower priority (I found this website helpful https://www.eco-home-essentials.co.uk/how-to-install-insulation.html)

[Big Jimbo]

Most of the Muppets out there still don't understand air tightness and thermal bridging. We are all here to help. Best of luck. 

[Novice Becky]

Thanks!

[Sparrowhawk]

Welcome to the forum @Novice Becky! There's a few of us doing retrofits here on varying budgets.

 

Thermal cameras are great but I found a home-made blower door more useful for finding where my airtightness was poor (or in this house, finding the few areas where it was good 😀). I made mine from an old door and a mains-powered Screwfix fan.

Your gas usage makes ours look good, but I suspect you are sensible and keep your house at 18C+ throughout the winter. Have you done heat loss modelling room by room to work out where your biggest losses/biggest wins are? I did mine in a spreadsheet but for £12 https://www.heat-engineer.com/ looks like it would save a lot of time. Tweaking the U-Values afterwards showed that floor insulation (which I'd been prioritising) was going to do v little, while CWI and airtightness would make a massive difference to heat loss.

 

Finding windows fitters that know more than screwing the window into the wall and squirting a bit of foam around - 'nuff said. I want to install my own windows next time.

 

Quote

the company will also fill the smaller empty cavity that is behind the wooden cladding at the front of the house

 

Flagging this as you'll need an air gap between the cladding and insulation to make sure it doesn't rot (something I'm dealing with here at the moment, only MDF wall with UPVC cladding directly attached). Have you checked the makeup of that section of wall?

 

Thanks for sharing your experience of the retrofit assessment you had, I'd been thinking about whether one was worth it to stop me procratinating give a "this is how to get there" guide, but came to the conclusion they were unlikely to have all the answers either - or worse, would have less knowledge than I've gleaned from this forum.

[Novice Becky]

Thank you for your comments @Sparrowhawk.  Great to be part of a 'retrofit community'.

 

Thanks for flagging up insulation behind wooden cladding. I wasn't very clear.  There is a brick & brick cavity wall behind the wooden cladding. The CWI firm put a camera in that cavity too. It's only 6cm wide and currently empty but they said they can fill it.

 

I read the DIY blower door posts with great interest a while back. I'll have to take another look at them as I was contemplating having a blower door test at some point. But a basic Flir camera was more instant and luckily it was -7C outside!

 

Gas usage - I'd love to keep the house at 18C but it's too damp! The living area is around 21C in winter, the bedrooms are 18-20C but there are lots of cold spots so it feels colder. I'm hoping for it to feel comfortable with the heating turned down once we have MVHR, new CWI and improved airtightness/thermal bridges.

 

Floor insulation - apart from the hassle of ripping up every floor covering, floor insulation seems to have a very long payback period (not that all this stuff has to pay back - as I see it, I'm in debt to the planet). So not much incentive at the moment.  Is there a cheap/easy way of insulating concrete floors?  Thermal imaging showed more heat loss around the edges of the floor which concurs with what the retrofit surveyor said (most heat loss will be where the floor meets the wall). Maybe the floor coverings are helping?? - we have Timberlay Gold under all the bamboo flooring (kitchen/living/hallways/study) and I did cork T&G flooring in 3 bedrooms during lockdown. And the suspended concrete floor in the extension (2009) would be insulated to building regs standards.

 

Heat loss modelling - good suggestion. I like a good spreadsheet so I'll look into this.

 

My Retrofit Survey was by a relatively large 'eco' company specialising in retrofits. I was expecting some detailed, specific advice but it was really generic, based on lots of assumptions. The person who came and took measurements was actually an estate agent who had been trained to measure and take videos of my home! The person who wrote up my survey was qualified in building and retrofit and I had an hour or two on Zoom with them but he wasn't able to advise on specifics. So it hasn't given me the reassurance I needed and hasn't stopped me procrastinating! I think you gain a lot more from reading around on Buildhub with lots of opinions. There's always more than one way to do something eg. Retrofit Surveyor didn't think MVHR was suitable and MEV would be better. Two other experts (not selling me anything) and LETI suggested MVHR is entirely appropriate.