Best value cavity wall insulation

[K78]

What is the best value cavity wall insulation at 200mm?

 

The kingspan boards are too expensive. Would 200mm of earth wool be a good idea?

 

Thanks

[Visti]

Below or above DPC? 

 

We went with EPS below for waterproofness, and cellulose above.

[K78]

Just now, Visti said:

Below or above DPC? 

 

We went with EPS below for waterproofness, and cellulose above.

 

Above DPC. I’m using eps blow ground level on walls and foundation. 

[PeterW]

Use EPS board below DPC and EPS blown beads above DPC. 

[Visti]

If you want to blow/inject it, you could go for technitherm by isothane which is an expanding polyurethane. Great u value and quick to install but is expensive compared to blown beads As you have to get it installed by a licenced installer. There are other less expensive polyurethane foams out there, but depend on whether they are above or below DPC

[nod]

2 hours ago, K78 said:

What is the best value cavity wall insulation at 200mm?

 

The kingspan boards are too expensive. Would 200mm of earth wool be a good idea?

 

Thanks

We full filled with earth wool

Very warm house

[epsilonGreedy]

12 hours ago, PeterW said:

... and EPS blown beads above DPC. 

 

I am still tempted to go for blown beads but do not think a new build within 20 miles in mid Lincolnshire has been built with these. The standard response from builders (pro and amateur) is a confused face followed by "isn't that what they pump into older cavity walls"?

 

A visiting EPC assessor commented, "you will get voids". Must been a regional thing.

[PeterW]

Just now, epsilonGreedy said:

 

I am still tempted to go for blown beads but do not think a new build within 20 miles in mid Lincolnshire has been built with these. The standard response from builders (pro and amateur) is a confused face followed by "isn't that what they pump into older cavity walls"?

 

A visiting EPC assessor commented, "you will get voids". Must been a regional thing.

 

I’d love to know why they think there will be voids as the drilling pattern excludes that. I have drilled a couple of places and they are definitely there - FLiR camera will show the gaps if there are any, may do that in the winter to see what is shown up as they are guaranteed anyway.  

[epsilonGreedy]

4 minutes ago, PeterW said:

I’d love to know why they think there will be voids as the drilling pattern excludes that. I have drilled a couple of places and they are definitely there - FLiR camera will show the gaps if there are any, may do that in the winter to see what is shown up as they are guaranteed anyway.

 

 

Indeed and as photos posted here previously demonstrate, voids in fitted of cavity batts occur. Thinking about this some more I reckon the risk of voids in blown beads reduces in cavities wider than 100mm.

 

How much faster would a brickie team work if not fitting insulation cavity batts as they go?

Edited July 25, 2019 by epsilonGreedy

[joe90]

I am another who used 200mm earth wool above DPC and extruded poly below as per golcar https://www.greenbuildingstore.co.uk/golcar-passivhaus-ground-floor-foundations/

 

bricklayers were good (no snots in the cavity) and inserted it as they went.

 

Edited July 25, 2019 by joe90

[PeterW]

35 minutes ago, epsilonGreedy said:

 

Indeed and as photos posted here previously demonstrate, voids in fitted of cavity batts occur. Thinking about this some more I reckon the risk of voids in blown beads reduces in cavities wider than 100mm.

 

How much faster would a brickie team work if not fitting insulation cavity batts as they go?

 

A lot quicker - just make sure they keep snots out of the cavity. 150mm is ok, 175mm gets you more and 200mm is ideal but needs longer wall ties. I’ve got the name of an excellent company in Sheffield if you want an installer. 

[joe90]

8 hours ago, PeterW said:

How much faster would a brickie team work if not fitting insulation cavity batts as they go?

 

My build included inserting the insulation as a fixed price no not worried about speed!