Component A
Component A for the primary air barrier; Component C for cavity filling where the decision is cost per bay.
See specificationSteel frame houses
Sealing light steel frame houses from inside
A light steel frame is a set of cold bridges with a house around it. The envelope is only as good as the cavities you actually filled.
What goes wrong on site
Three failures, in the order they appear
- 01
Cavities behind the boards stay empty where a gun cannot reach.
- 02
Whole-envelope air-tightness is the test that fails first.
- 03
The schedule is tight and the trades are stacked on top of each other.
Why one-component foam, and not something else
Three properties, no chemistry
- Mobility: a can and a gun reach a joint that a panel, a board or a truck cannot.
- Irregular geometry: it expands to the shape of the void, including penetrations.
- Closed cell: air barrier and moisture barrier in one pass, without a second trade.
How it is done, and what to hold
The four numbers this job lives on
| Step | What to hold |
|---|---|
| Surface | Cavity clear of offcuts and dust, service penetrations identified and sleeved. |
| Fill volume | One third of the joint depth. The foam expands to fill; filling it to the top bends frames and wastes material. |
| Passes | Two passes of 30 mm at most. A single thick pass traps heat and collapses in the core. |
| Trim | Cut after the window on the parameter card. Never pull or press uncured foam. |
| Cover | PU is not UV-stable. Any exposed face gets sealant, render or a trim within 48 hours. |
Typical guidance. The parameter card for your grade carries the tolerances your operators work to.
Common failures
Three ways this job goes wrong
- Spot-filling a few bays and declaring the envelope airtight.
- Foaming before the services are in, then cutting the runs back out.
- Leaving the foam exposed in a roof void where the sun heats it to 60 °C.
What to tell your customer
Three sentences you can copy into a quotation, a WhatsApp message or a site meeting. Your competitors' websites talk about themselves; this block is for you to talk about the job.
„We fill the cavity before the boards go on, not after.“
„Every service penetration is sleeved and sealed separately.“
„The air barrier is continuous — the blower-door result depends on that line.“
Send the drawing or the photo — we will reply with the parameters.
Technology brand
Tell us the joint, the substrate and the season
- 1 tonne minimum, five 200 L drums
- SDS, COA and Form E with every shipment
- We reply within 24 hours, Monday to Saturday.