Small house- 74m2 over two floors- 2 up 2 down 1900 solid-wall semi. With a large garage (another 30m2) down one side that I want as a 'clean and nominally heated studio/workshop' that needs a new roof. On the right (downstairs) is a very narrow gennel. On the front is the complexity of lots of electrical wiring that will be bureaucratic and probably expensive to move. Uninsulated concrete floor downstairs. Heating is a log burner with boiler- wood is free in money terms, but not in effort (there is a gas supply). South facing roof.

I've got 30K and want a comfortable house with the lowest bills. Happy to DIY almost anything, I'm capable and practical and find it all fascinating.

With a south facing-roof solar pv is worthwhile, can fit 4.2kWp of panels on the roof and there's adjacent south-facing land that I could fit more on. I think that 6kW of panels with excess going to heat dhw will give me largely free hot water for most of the year.

Insulation would be next on my list. 400mm loft insulation is easy.
Garage I'd do a flat or pitched roof with 150mm pir in, and some form of roof lantern/velux. And IWI. The garage has no direct heating and that’s fine.

Need new windows on the north side- pvc triple glazing. The lack of condensation on the windows ever is worth it.

EWI would need the roof extending, the wires moving on the front and I've no idea what to do with the gennel (internally the narrow stairs are there). Would rockwool and lime render play nicely with the 'old houses are always damp' line I keep reading? XPS below dpc? I've no idea how far down the house goes yet- there's unlikely to be much in the way of foundations.
IWI would mean no thermal mass (wfh so in the house all day everyday largely), the kitchen/bathroom would have to wait until those rooms needed some work (I don't want to rip out a perfectly good bathroom for a few years). And the rooms are already tiny- but I could sacrifice enough for 50mm pir. Which is better than nothing, but not inspirational. (Still no idea what to do on the stairs-wall).


Any ideas/inspirational stories/words of warning/things I should go and think/read about?
Many thanks.

400mm of loft insulation, great idea

I would try for EWI if you can, I like 200mm EPS and take it down to the footings, it could stop just below the gutter. Possibly not go all the way up the gable.

Solar is unlikely to provide much hot water in the winter.

Hope it goes well

Hmm, that link eventually leads to https://passivhaus.uk/wp-content/uploads/2024/10/Heat-pumps-and-Retrofit-v1.2-240605.pdf which makes it clear that when to buy a heat pump depends on the individual project including details of how the project is funded. Not quite as simple as "Fabric Fifth"!

>>> that link eventually leads to https://passivhaus

Have another look, that PHT article is linked because it's the counterfactual approach that he is comparing against.

In Fig 1/2 he shows that 'Fabroc fifth" gets 80% of the benefits for £15k , whereas the approach in the PHT paper ("PHT/AECB") needed £55k to get the same effect.


This is as expected, the PHT is about getting the best possible performance out of (typically) new builds whereas the fabric fifth people are more interested in getting large numbers of retrofits done whilst getting as far as can be with (typically) limited time/money. They do discuss that.


ETA

For the OP 's £ 30k budget then one plan could be
1) heatpump £5k after grant
2) smart metering EV charging etc £2k
3) top up insulation, garage roof, draft proof and ventilation, maybe thin iwi in main room,etc £10k DIY
4) solar+batteries £10k


Then EWI and high spec windows later, £10k each, if funds/needs become available

Heatpump may be £5K installed after the grant, but ties me to paying for the electricity to use it. Versus wood which is free (though requires effort to cut- but then woodland maintenance is a fact of life when you own one, and needs doing anyway).

I need to consider if a heatpump (but having higher electricity bills) is worth the no-dust/no lighting of wood burners/warmer house in the morning/better air quality (when the neighbours all burn coal for heat).

SCOP= 3 is a conservative assumption - the present market norm from Octopus et al is around 3.6. This strengthens the case for heat pumps and weakens the residual case for fabric measures.

Posted By: WillInAberdeenSCOP= 3 is a conservative assumption

What the PHT document explains is that the expected SCOP depends on the conditions in the individual building and it is the variation in the predicted SCOP that determines the best time to install it.

The expected SCOP does not depend on the conditions in the building any more, that was the old generation of heat pumps. The R290 heatpumps can get high SCOP in most buildings now.

Glyn Hudson (he of OEM) did a good YouTube of his scop=5 heatpump in a bogstandard seventies bungalow, worth searching for.

Hi Charli,

Is this your forever house? Wood collection, splitting, storage, access in winter becomes a major chore as you age. My in-laws have a log fired boiler in Hungary. They have wood delivered, but still have to split it, stack it, and go outside to collect logs in winter and now they are both in their 70's it is areal struggle (and risk) for them. Worth thinking ahead. Much as I understand fabric Fifth, we also have to consider our aging population, and insulating well reduces the burdon.

EWI on that front wall with the mains cable attached us probably a non starter - it can be done, but would be a major PITA. Pragmatically, I would IWI on the front wall (with internal returns), and EWI the rest.

This looks like typical Flemish bond brickwork, but photo quality is poor if zoomed in. It could be Rat Trap, but I doubt it. Won't be cavity either way. Ratrap may need more investigation before EWI.

Also lintels have been replaced and external settlement repairs - I'd be investigating the structure before covering anything up.

I'd also caution against fitting solar until the roof is looked at. It might just be a distorted photo, but it looks like the roof is bowing. I suspect it is a typical shallow victorian roof designed for (light-weight) slates, and the concrete (Redland 49-type) tiles have been added without regard for the extra dead weight. This is, unfortunately, a fairly typical occurance in our country, where tradesmen are only interested in making money rather than doing a good job.

It'll be a good test for your chosen solar installers. If they recomend strengthening the roof before the panels can go on you know you've got a good team. I used to turn away work for similar reasons back in the day, and wait for the homeowners to come back to us later for rectification works when they went with one of the cowboy installers who threw as many panels as they could get on the roof regardless.

Probably only needs a couple of props for the purlin - if there is one. Quite common for this type of roof to have very thin rafters and no purlin support.

Posted By: Charlican fit 4.2kWp of panels on the roof

Have you allowed for the clear space around the edge of the roof?

Posted By: WillInAberdeenand another chunk of the cost is

scaffolding.

With all those costs, the least of it is the thickness of the insulation itself - so it's truly false economy to economise by going thinner - unless going thicker crosses a threshold where the other, fixed costs have to increase e.g. having to extend the eaves overhang, when you don't if it's thinner.

Forever home… good question… I imagine I wouldn't want the upkeep of 2.5 acres and a house with steep stairs once I'm past 70, so assume I'll move out to a bungalow at some point. Having wood fuel, but it only being a middle-effort sort of job to change it to something else in 20 years might be worthwhile (but 20 years is a long time!).

The awful roof covering, removal of chimney, larger windows and concrete floor was all done in the 1970s under a 'restoration grant'.
I would love to replace the roof back with reclaimed slate (or solar slates?), but its not really in my budget right now. I could perhaps put the solar panels in the plastic trays- flush with the roof covering and redo the front elevation in slate (as there wouldn't be much roof covering left at this point).
The survey did say 'get the roof checked because tiles are heavy', as did the previous survey in 2006- and it doesn't seem to have moved. I will check it, but I'm not worried about it. Same goes for the settlement you can see in the front elevation- it looked exactly the same on photos from 20 years ago.

Should actually get the keys soon, I can then measure things and be nosier and can start getting some quotes and talking to some local installers.

I've booked a 'baumit EWI' course in a few weeks- the one that assumes you're a renderer. Whilst I don't expect to learn to render- I thought having a good conversation about how to do all the fiddley edges/corners/window would be useful. Much more interesting than the day job.

I should have 6 months or so of working on it (admittedly whilst having a full time job), without having to live there. So that helps.

I'm not going for ROI or the environment (sorry!), but as WillinAberdeen says- I just want a comfy house! Having old houses continue to be livable in the future (and I'll be technically carbon-neutral with wood-heating, though more polluting- it all depends what you cound) seems useful.


The plan currently is:
1- New garage/flat roof- needs new timbers and 150mm pir- at a much steeper pitch from the house (needs planning permission). Roof covering of reclaimed slate or (would love seamed zinc, unlikely to afford it). IWI inside of garage space. Front of garage to be bricked up/smaller door/etc (usage of space related).
2- Put solar panels on the roof (integrated trays?)
a. Extend the roof over the gable end ready for EWI later? Following https://cms.trustmark.org.uk/media/yo2eytf3/the-iaa-bpg-extending-the-roof-line-to-accomodate-ewi-v1-the-iaa-dec.pdf?sfvrsn=13149407_2
By using integrated trays I've got spare tiles to extend the roof? Even if I don't EWI- I'd do this work myself so I'm not losing anything, same scaffold.
b. And fit a DHW tank, with solar immersion
3- Replace some windows (the back of the house) with triple glazing.
a. Where to position the windows? Not certain of EWI yet so would need to be in the brick, but that’s wrong for if I do EWI!

Live with it like this for the winter- how much heat does the house lose overnight? How cold are the walls? Do IWI returns as decorating.
Next summer- EWI if I go there.

I've always been aiming at 'stay warm in winter', but given recent high temperatures I'm now thinking of summer thermal mass too! My current house has IWI and a concrete slab and stays lovely and cool for a week even in 30c+. I need to think of summer comfort as well.

Muchas gracias for all your thoughts.

Posted By: CharliForever home… good question… I imagine I wouldn't want the upkeep of 2.5 acres and a house with steep stairs once I'm past 70, so assume I'll move out to a bungalow at some point. Having wood fuel, but it only being a middle-effort sort of job to change it to something else in 20 years might be worthwhile (but 20 years is a long time!).

If you have been in your new home for 20 years and still like the place / area then when you are 70+ managing the house (e.g. a stair lift) will be way cheaper and a lot less stress than moving to somewhere new.

Don't assume you have a solid wall until it is proved. I had a house (in the UK) that had flemish bond brickwork and everyone (building society surveyors / valuers included) assumed it was solid wall however when I knocked off some plaster the inside skin was stretcher bond and I found a 3" cavity. The outer flemish bond skin was made with snapped headers. (built about 1830ish)

You say the wood for heating is free (except for the work), are you expecting the wood to come from the 2.5 acres? If so that is not a lot of area to sustainable support wood fired heating unless the house is well insulated and even then you will probably find that you can only heat with wood for 2 -3 months of the year.

What to do with the 2.5 acres when you are 70+ ? - start now in planning the future. If it is all or mostly wooded then get the right trees planted in the spaces you have cut out for firewood so that in 20 you have a well managed low maintenance wooded area. Any grassy areas can be selectively mowed to promote wild grasses and flowers to end up with, over time, a wild flower meadow that will need mowing twice a year, and for that you get a small (15hp) tractor with a topper. If you get a wild flower meadow every one will say how lucky you are to have such a wonderful meadow alive with all sorts of insects - except they won't know that it got that way after 10+ years of careful management.

XPS is not needed below the DPC, in fact many (including myself) believe EPS is better both below DPC and below ground. When I have done EWI I have put up the EPS and then got a builder to render. (But get a builder to agree to the part job first). If you are thinking of EWI then play with
https://www.ubakus.de/en/r-value-calculator/
(Use the demo version) to see what the diminishing returns are to decide whether a roof extension is worth the extra cost. (Assuming you have a solid wall)