1950's Refurb with hints of eco...

[Bowsers]

Morning all,

 

Great to be here and thanks for accepting me into the forum 😊

 

So our story; we bought a 1950's 4 bed detached house in Bristol in 2015. It was perfectly liveable but had so much more potential, so the plan was to lots of work to it. But with two young kids, time and money wasn't really there.

 

Roll on 10 years and we're now picking things back up. This summer we appointed an architect who has worked up a kitchen extension and new utility room. Planning granted in August and now we're on our way to getting a contract in place. Hoping to start work in April '25.

 

Here's an overview of the scope:

 

- New triple glazing to replace existing tired DGUs

- MVHR

- ASHP to replace exiting 15yr old gas combi

- 100mm EPS  EWI over the exiting '50mm cavity walls with bead insulation'

- Dig up 80% of ground floor to lay UFH over 100mm PIR

- EV charger (with EV eventually!)

 

We currently have 6kWp of unobstructed PV facing SE connected to 16.4kWh of battery storage.

 

Current stats:

 

- 200sq.m (Net internal heated area)

- Gas cons - c.15MWh/yr

- Elec cons - c.5.3MWh/yr

- Elec gen - c.5.1MWh/yr

 

The house in its current form is pretty leaky. Lots of the DGUs have warped and when the wind blows we go into thermal-sieve mode. I'd be tempted to take tape to them, but I reckon the infiltration is keeping the house dry. High energy, but healthy!

 

So there we go. Lots of questions to ask and loads to learn from the forum.

 

Looking forward to learning and thanks in advance.

 

Bowsers.

 

[Iceverge]

Welcome welcome.

 

Sounds like a good plan. 

 

I would the only thing I might focus on more is Airtightness and more insulation under the floor. 200mm PIR or 300mm EPS would b a good level. 

 

 

[Bowsers]

Thanks @Iceverge. Both fair points. Going deeper with the ground insulation is certainly in mind. I'm just unsure as to feasibility of digging down that far. I don't think the existing foundations are that deep!! I need to look into details for how that depth could be accommodated.

 

On the airtightness front, again keen. I'm hoping between the new EWI and taped triple glazed units going in that we can improve airtightness significantly from where we are now. I guess where I used the term 'hints of eco' in the subject, I'm not sure how much mental energy I've got to chase down all the meticulous details required to get towards passive levels. I'd admire those that really throw themselves at these things, but I need to be realistic on the timeframes we're dealing with.

[Iceverge]

I would say it's very unlikely that you'll be anywhere near the foundations at that level. It'll be more digging out but it's worth it I would say. 

 

Consider something like seconds&co for a deal on PIR boards. I would work on 200mm as a good figure as 100mm boards typically have a good price to depth ratio. 

 

There's no rocket science to airtighess. Basically just seal up all the gaps. 

 

 

 

 

 

 

[SteamyTea]

Welcome

 

Just to add to

37 minutes ago, Iceverge said:

There's no rocket science to airtighess. Basically just seal up all the gaps. 

While it is identifying the leaks that is hard, two other things need to be considered, condensation management and wind washing/air bypass of insulation.

[Iceverge]

34 minutes ago, SteamyTea said:

condensation management

 

Largely an airtighess and ventilation issue. 

 

34 minutes ago, SteamyTea said:

wind washing/air bypass of insulation

 

Full fill fluffy every time for me in this regard. EWI boards should be foamed at the perimeter and at all joining faces for install too. 

[SteamyTea]

22 minutes ago, Iceverge said:

Largely an airtighess and ventilation issue. 

And gas movement, why they vapour 'openness' is important.

The further towards the cold side, the more vapour open it needs to be to aid evaporation.

[Adrian Walker]

I would look at using foamed glass for floor insulation, particularly if you are digging out as much of the foundation as you can and leaving the walls.