Builders quotes - trying to be accurate & spec'ing right materials

[dan_cup]

Hi all,

so im going out to a few builders to quote for our rear/side extension.

 

We have the planning drawings (basic) and a structural eng drawings for founds/steels.

 

Couple of the builders have asked me what insulation (thickness/type) are to be used and the type of internal blocks (strength rating). this would help them get a more accurate price.

 

From my side the architect didnt provide these since he said that we/the builder could go down the Building notice route which means the builder needs to know these detail them selves?

 

The other route is building regs submission i think? would this be the job of the architect to then come up with the requirements? 

 

Im torn what to do since two builders have priced up without me potentially having to budget for extra architect work.

 

Any opinions?

[nod]

Tell them Solid concrete blocks 7 n

You cavity will dictate your insulation thickness 

T&G cavity batts Echotherm or similar 

You need to leave 100 mil cavity airflow So 150 cavity 100 mil insulated board Or you can full fill with a wool batt (Cheaper)

[nod]

20 hours ago, nod said:

Tell them Solid concrete blocks 7 n

You cavity will dictate your insulation thickness 

T&G cavity batts Echotherm or similar 

You need to leave 100 mil cavity airflow So 150 cavity 100 mil insulated board Or you can full fill with a wool batt (Cheaper)

This is one I’ve done this morning 

Trusses But same principle 

[dan_cup]

On 07/10/2024 at 16:28, nod said:

Tell them Solid concrete blocks 7 n

You cavity will dictate your insulation thickness 

T&G cavity batts Echotherm or similar 

You need to leave 100 mil cavity airflow So 150 cavity 100 mil insulated board Or you can full fill with a wool batt (Cheaper)

 

What do you mean here? On the Ecotherm site there a picture of builder using a board that fully fills the cavity?

 

Am I right in thinking its 100mm block, 150mm cavity, 100mm brick.

So if we use 100mm Eco therm then 50mm is free air space?

 

 

 

[MikeGrahamT21]

The T&G PIR boards are designed as full fill with approx a 5mm gap, I used xtratherm ones on my latest build, now unilin but these ones are the same.

 

have a look at their install guides, there will be buildup examples, but I know it’s full fill as it was one I’d considered using myself