Couple of big projects - Budgeting

Yaayuh! · 18 Jun 2020 at 17:08

Hi all, we're just considering a budget for a couple of big jobs on the house and I whilst I look around and before I get quotes, thought I might as well ask you lot as well.

Project 1 - Insulation
Our house leaks heat, pretty bad and unfortunately this isn't your average loft insulation job. The house is an old (but extended) detached 3 bed cottage, the 1st floor is in the eves and the loft is barely a crawl space. There is also a few single story parts with no loft access.
Therefore the way I feel it will go as to not re-do the interior is to remove all roof tiles for access and apply insulation boards and then replace the tiles.

Project 2 - Windows & Doors
We want to have 12 windows and 2 external doors (front door and rear french windows) replaced, with something prefereably decent.
One of the said windows is actually another set of french windows that we want to brick up and have a standard window put in.
Once this is all done the stone render will need to be put good and a full paint of the house.

I can add a picture later as a guide, but I have no idea how much to expect such jobs to be.

Any rough estimates?

edit: picture added. The other side is essentially the same, mirrored.

eviled · 18 Jun 2020 at 17:45

Project 1 - essentially the price of a new roof which depends of size, pitch, material its made of, features ie gullies etc. and any unexpected surprises they uncover.
Budget for scaffolding, replacing a reasonable amount of tiles that are damaged or get damaged during removal (think mine was ~20%), flashing, breather membrane, battens, insulation + whatever I've forgotten

Project 2 - again depends on type of window, materials, type of glazing etc. - a 1.5m x 1m double glazed hardwood casement cost me ~£800 fitted but unpainted recently.
Don't put too much emphasis on windows keeping your house warm, they usually account for a small proportion of the heat loss when talking solid wall construction. Draught proofing is more important and cost effective, but new windows should be nice and tight.

Have you considered external insulation? It's extremely effective and ideal on old buildings.

Yaayuh! · 18 Jun 2020 at 18:42

eviled said:
Project 1 - essentially the price of a new roof which depends of size, pitch, material its made of, features ie gullies etc. and any unexpected surprises they uncover.
Budget for scaffolding, replacing a reasonable amount of tiles that are damaged or get damaged during removal (think mine was ~20%), flashing, breather membrane, battens, insulation + whatever I've forgotten

Project 2 - again depends on type of window, materials, type of glazing etc. - a 1.5m x 1m double glazed hardwood casement cost me ~£800 fitted but unpainted recently.
Don't put too much emphasis on windows keeping your house warm, they usually account for a small proportion of the heat loss when talking solid wall construction. Draught proofing is more important and cost effective, but new windows should be nice and tight.

Have you considered external insulation? It's extremely effective and ideal on old buildings.

Thanks for input, much appreciated.

Re: Project 1.
Noted a few points I hadn’t taken into consideration. Also, though all tiles seem good, some may break.

Re: Project 2.
We’d likely go for UPVC. Regarding the emphasis on the windows, it’s probably 50:50 sound and heat.

As for external insulation, we have cavity wall insulation but the vast majority of the heat is lost via roof space.

edit: picture added.

thezappa · 18 Jun 2020 at 22:00

If you strip the roof consider if you want a covered scaffold. If you do prepare for a large bill.

Quartz · 18 Jun 2020 at 22:12

Yaayuh! said:
Therefore the way I feel it will go as to not re-do the interior is to remove all roof tiles for access and apply insulation boards and then replace the tiles.

Can you not just spray insulating foam on the inside? That might get around any access issues.

2004typer · 19 Jun 2020 at 10:10

Quartz said:
Can you not just spray insulating foam on the inside? That might get around any access issues.

I'd be worried about condensation issues with this - and I'm assuming with the rooms in the roof a lot of the plasterboard is directly on the underside of the rafters.

Even with a re-roofing exercise you might not achieve a lot - the rafters might not be very deep, thus the deepest insulation you'll get in might only be 50mm or so (after considering ventilation requirements as well).

Might have to bite the bullet and strip back the plasterboard internally - you'll then be able to add additional timbers to the underside of the existing rafters to create a deeper void, and you'll also be able to fully underdraw them with a continuous insulation board as well - will be much more effective.

Assuming the roof has a non breathable felt as existing - be aware that you will need a minimum 50mm clear gap between the top of the insulation and underside of the felt, coupled with cross flow ventilation.

But - if the roof is knackered and you decide to replace this as well, you could get away with a 25mm gap if you were to use a breathable felt (and potentially no cross flow ventilation if the felt specified has the relevant BBA cert to allow this (basically a breathable felt should allow moisture to disperse through the membrane and not condensate).

But - you could also foil tape all the insulation board joints (assuming using a kingspan/celotex type insulation) to limit the amount of moisture getting into the void (to act as a vapour control layer).

Yaayuh! · 19 Jun 2020 at 10:19

2004typer said:
I'd be worried about condensation issues with this - and I'm assuming with the rooms in the roof a lot of the plasterboard is directly on the underside of the rafters.

Even with a re-roofing exercise you might not achieve a lot - the rafters might not be very deep, thus the deepest insulation you'll get in might only be 50mm or so (after considering ventilation requirements as well).

Might have to bite the bullet and strip back the plasterboard internally - you'll then be able to add additional timbers to the underside of the existing rafters to create a deeper void, and you'll also be able to fully underdraw them with a continuous insulation board as well - will be much more effective.

Assuming the roof has a non breathable felt as existing - be aware that you will need a minimum 50mm clear gap between the top of the insulation and underside of the felt, coupled with cross flow ventilation.

But - if the roof is knackered and you decide to replace this as well, you could get away with a 25mm gap if you were to use a breathable felt (and potentially no cross flow ventilation if the felt specified has the relevant BBA cert to allow this (basically a breathable felt should allow moisture to disperse through the membrane and not condensate).

But - you could also foil tape all the insulation board joints (assuming using a kingspan/celotex type insulation) to limit the amount of moisture getting into the void (to act as a vapour control layer).

Indeed. It's currently plasterboard -> cavity -> membrane -> tiles. I wouldn't spray anything in there.

The cavity could support 25-50mm insulation board keeping a gap for ventilation, which although is not much will still have a big effect. If there's any ventilation worries then an airbrick can be inserted at the gable end and vent tiles could be used, there are options.

I would like to avoid the option of doing from the inside if possible, but I am aware that this may be unavoidable.

Jez · 19 Jun 2020 at 10:30

Re the windows, UPVC are quite cheap but appear to be what you already have installed? You wont really gain anything by changing these if your existing ones are in good condition. You can line up online quotes for the supply of windows all over the internet as a delivery only purchase. A pair of fitters IME will do around 3-4 per day, so budget £400 labour per 3-4 windows.

This will give you a guide (a fairly accurate one) before you engage some local FENSA registered installers.

Yaayuh! · 19 Jun 2020 at 11:16

Jez said:
Re the windows, UPVC are quite cheap but appear to be what you already have installed? You wont really gain anything by changing these if your existing ones are in good condition. You can line up online quotes for the supply of windows all over the internet as a delivery only purchase. A pair of fitters IME will do around 3-4 per day, so budget £400 labour per 3-4 windows.

This will give you a guide (a fairly accurate one) before you engage some local FENSA registered installers.

Yeah, the windows are old and **** lol

Most are drafty, 4 blown panes, two won't open and even the static panes are terrible with where sound insulation is concerned. One set of french windows are nackered and we want to do away with the other set of them.

Jez · 19 Jun 2020 at 12:01

Haha, they sound bad, its not worth putting up with old windows with the price of new ones being so reasonable. Google for "buy upvc online" and loads of sites will pop up. Add my suggested labour to that and you have a fairly accurate number to compare with local firms. Ultimately get a local fitter to supply and fit as he will issue the FENSA certificate for you.