Rebuilding outer leaf

[allthatpebbledash]

In planning stages of a deep retrofit. House is detached, and neighbouring houses are brick, various shades of red and brown. Some have been rendered to the sides over years.

 

My house is the same I suspect. Make up of the existing walls is ‘50-60s brick cavity walls with some mineral wool blown in place, and other half (previously built extensions) is dual skin blockwork with 50mm PIR in the cavity. Approx cavity in all the walls is 75mm.

 

All the walls are covered in pebbledash!
 

As part of deep retrofit, I will be having all new ground floor structure and intermediate floor, a full new roof, all new windows and doors, and rebuilding the rear wall of the house due to structural complications and building a modern rear extension. That’s just to give idea of what project entails.

 

Question is, how should I freshen up the rest of the house?

 

Option 1.

Remove pebbledash, inspect underlying brickwork/blockwork and make good, render over.

 

Option 2.

Remove pebbledash, inspect underlying brickwork/blockwork and make good, leave original brick as finish. Where there is blockwork, render over.

 

Option 3.

Leave pebbledash in situ, inspect to make sure no cracks etc, fix EWI straight on top and render over.

 

Option 4.

Take down external leaf, replace insulation with full fill cavity batts, probably wool, inspect wall ties etc, rebuild with nice red brick as finish.

(Being red bricks are cheapest around, but it’ll allow the house to blend right in the street scene too.)

 

Option 5.

Take down external leaf, replace insulation with full fill cavity batts, probably wool, inspect wall ties etc, rebuild external using blockwork and render over.

 

I have some understanding of the costings involved based on initial conversations with a few trades. Based on 200 sqm of external wall.

 

Remove pebbledash £20 sqm

Render £60-140 sqm (pending type)
Blockwork £25 sqm

Bricks £30-£60 sqm (pending type)

EWI £40+ sqm (min 50mm)

Wool batts £18 sqm (min 75mm)

 

I feel option 4 would be the best overall.

 

But.

 

Would love to hear some thoughts and ideas if there are other ways? Or if someone else has done something similar, how did it go? Lessons learned?

 

Thanks.

 

[Conor]

Option 6. Demolish the lot and start again. What you are planning to do will cost more and perform worse than a new build.

[Canski]

You are not going to get brickwork or blockwork supplied and fitted for those rates. I'm unsure about the other items.

[Redbeard]

Are you doing all the work yourself? I am not sure where the £40/m2 for EWI came from, even at only 50mm. The '+' must be a very big +! For years 'around £100' has been the regular cry and it very rarely comes in at that. Including 'enabling works I have seen it well over £160/m2.

[Iceverge]

2 hours ago, allthatpebbledash said:

Question is, how should I freshen up the rest of the house?

 

 

2 hours ago, allthatpebbledash said:

Option 1.

 

2 hours ago, allthatpebbledash said:

 

 

2 hours ago, allthatpebbledash said:

Option 2.

2 hours ago, allthatpebbledash said:

Option 3.

2 hours ago, allthatpebbledash said:

Option 4.

2 hours ago, allthatpebbledash said:

Option 5.

[joe90]

Yes I was thinking knockdown and rebuild properly And get the VAT back.

 

[Russell griffiths]

You are 100% not going to do option 4 or 5 never heard such a ludicrous idea. 
there’s been a few silly ideas on here in the past, but I’m afraid you have just topped them all. 

[Mike]

5 hours ago, allthatpebbledash said:

Option 2.

Remove pebbledash, inspect underlying brickwork/blockwork and make good, leave original brick as finish. Where there is blockwork, render over.

 

Option 3.

Leave pebbledash in situ, inspect to make sure no cracks etc, fix EWI straight on top and render over.

One of these. Which one depends on the state of the pebbledash - in particular evidence of cracking or sounding hollow.

 

However a deep retrofit will be more expensive and time-consuming that rebuiding. Unless you do lots yourself, in which case it may be cheaper but will take much longer...

 

5 hours ago, Conor said:

Option 6. Demolish the lot and start again. What you are planning to do will cost more and perform worse than a new build

...so give this very serious consideration!

[Benpointer]

Option 4 or 5 will surely lead to Option 6 in an uncontrolled way.

 

If you really don't want to rebuild, then Option 3 but aim for more than 50mm EWI.  

 

 

[Mattg4321]

With that much work it’s going to be cheaper and better to knock it down and start again, doing it properly. 

[Iceverge]

@allthatpebbledash, I hope I wasn't poking too much fun with my above post. Sorry if I was. 

 

Practically what you are proposing is possible but very uneconomical. It's been alluded in the above posts that with lots of DIY that it could be cheaper. I made the mistake in our old build of not valuing my time enough. I embarked on circuitous routes because of it and it pretty much burnt me out. 

 

If you really want to avoid a knock and rebuild then I would step back from the bleeding edge of performance a little. 

 

Dig out the ground floor and replace with 300mm EPS. Pour a slab with UFH or float an OSB floor on top. 

 

Suck out the mineral wool in the walls, replace with EPS beads. 

 

Parge internal walls and apply good airtighess to all joists and wall penetrations. Apply a battened internal service cavity with mineral wool insulation. Plasterboard and skim 

 

Install good quality 3g PVC windows and doors.

 

Apply an airtight membrane to the ceiling of the existing roof. Pump 3-400mm of cellulose in there.

 

Install dMEV or ideally dMVHR if possible. 

 

You'll get to about 30kWh/m²/annum like this I reckon and it can be done piecemeal. 

 

Otherwise knock and rebuild. 

Edited 14 hours ago by Iceverge

[Ferdinand]

I think mine has the outer leaf rebuilt, but it was a bungalow having an extra storey added and was done by the previous owners who lived in a caravan for several years. They also did a side extension and a fat-at-the-back extension. We bought it finished except for a conservatory and the electric gates. The caravan is still on the Council database 15 years later.

The weakness I see with redoing the outer leaf is that it will never be high performance with only a 75mm cavity and 50mm EWI. That feels like more cost than benefit. I only have 80mm PIR (it needed double) in the cavity and is better than OK, but only an EPC of low-80s iirc without the large solar array.

Your costs need a careful check. I have had various EWI quotes for different houses over the years, typically for 125-200mm to be worth the pfaff, and they have never come out at less than £100 per sqm even going back a decade and with agreements for me to get various prep work done.

I'd say consider option 6 if you can, and a design-and-build from a timber frame company (or design-and-shell and you do fit-out-and-decorate), and bank the several extra years of spare time you get for you or your family to enjoy.

Ferdinand

 

[Jilly]

Maybe all the videos laboured the point …

Edited 4 hours ago by Jilly