Window reveal insulation

poor farmer

I'm at the early stages of blocklaying. Self build/direct labour. Going with 100mm block 250 cavity 100mm block. Filling the cavity with bead.
I was checking progress today and
Where the block is returned to close the cavity at windows/doors the blocklayers have 25 mm insulation (pir board) between the two leaves.
what thickness of insulation should there be between the two leaves.
I took pictures but I'm not sure how to upload them.
All advice appreciated.

braftery

poor farmer wrote: »

I'm at the early stages of blocklaying. Self build/direct labour. Going with 100mm block 250 cavity 100mm block. Filling the cavity with bead.
I was checking progress today and
Where the block is returned to close the cavity at windows/doors the blocklayers have 25 mm insulation (pir board) between the two leaves.
what thickness of insulation should there be between the two leaves.
I took pictures but I'm not sure how to upload them.
All advice appreciated.

Do you have drawings for the details of your building ?

This detail should be included in them.

If you don't have them contact your architect or engineer and ask for a full set to provide your block layers with all of the information to build your house to the specification you require.



You are building a house with a 250mm cavity, so I assuming that you are aiming for a low-energy building. A building of this nature is the sum of all of the parts and most importantly, how all these parts are integrated with each other.

No sub-contractor sees the whole house.. they are all looking after their bit of the job. How they all fit together is where the design team fit in.

Tackling a wide cavity, low energy building as a self build is a brave step for a person who understands all of the science and technology involved and is armed with a full set of detail plans for how the building will all piece together.

If you are not the above person and are not armed with the above information, I suggest you seek out a professional who can help you deliver the home you are hoping to build.

BryanF

some posts moved from an 8year old thread!

Gumbo

250mm cavity also required dedicated engineering design as per the building regulations. Make sure you have accounted for this.

Calahonda52

kceire wrote: »

250mm cavity also required dedicated engineering design as per the building regulations. Make sure you have accounted for this.

+1


From Part A: anything beyond 150 mm cavity requires design in accordance with SR 325/Eurocode 6

1.1.3.27 Wall ties should be provided in cavity walls and should comply with I.S. EN 845-1 and should be material references 1 or 3 in I.S. EN 845 Table A1 austenitic stainless steel. The minimum quantity of ties provided should be:
• 2.5 wall ties per square metre for cavity widths between 50mm and 75 mm;
• 3 wall ties per square metre for cavity widths between 75 mm and 100 mm, and
• 4.9 wall ties per square metre for cavity widths between of 100mm and 150 mm.
Extra wall ties are required at the jambs of openings and movement joints as shown in Diagram 9 (for use of ties in other cavity widths, see prS.R. 325).


Part A in full
http://www.housing.gov.ie/sites/default/files/migrated-files/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad%2C30177%2Cen.pdf