Explainer
Breather membranes explained
Two different things are called "house wrap". One is a weather membrane for timber frames. The other is external wall insulation.
In the building trade, "house wrap" can also mean a breather membrane: a thin sheet fixed to the outside of a timber frame or behind cladding. It stops wind and rain getting in while letting water vapour from inside the wall escape.
In Ireland, most homeowners searching for "house wrap" mean external wall insulation: the insulation and render added to the outside of an existing house. SEAI calls that measure "External wall insulation (the wrap)". This page explains the difference.
Two meanings, one name
| Breather membrane | External wall insulation (the wrap) | |
|---|---|---|
| What it is | A thin, breathable sheet | Insulation boards with a render finish |
| Where it goes | On the frame of a new timber-framed or clad wall, before the outer finish | On the outside of an existing wall |
| What it does | Keeps wind and rain out of the frame, lets vapour out | Cuts heat loss through the wall |
| Insulates? | No, not on its own | Yes |
| SEAI grant? | No | Yes: €3,000 to €8,000 |
| Who buys it | Builders and self-builders | Homeowners upgrading a house |
What a breather membrane does
A timber frame or a clad wall needs protecting from weather while it's being built and for its whole life. A breather membrane is wrapped around the outside of the sheathing and lapped and taped at the joins. It works like a good rain jacket: it holds back liquid water and wind, but lets water vapour pass out, so moisture from inside the house doesn't get trapped in the frame.
That's different from a vapour control layer, which goes on the warm, inside face of the insulation to limit how much vapour gets into the wall in the first place. A typical timber frame wall uses both, on opposite sides.
Where you'll come across one
- New timber-frame houses and extensions
- Walls finished with timber, fibre-cement or metal cladding
- Under some roof tiles and slates, as a roofing underlay
- Garden rooms and timber outbuildings
Membranes in external wall insulation
Most external wall insulation on Irish block and brick houses doesn't. The boards are fixed to the wall and finished with a reinforced basecoat and render, which is the weather layer. Systems over timber frame or with cladding finishes are different, and the maker's details decide what layers go in. Ask the contractor what the system's build-up is.
Which one you need
- Building or extending in timber frame? You want a breather membrane, specified by your designer or the frame maker.
- Cladding a garden room? A breather membrane behind the cladding, with a ventilated gap.
- Want a warmer existing house and a lower heating bill? You want external wall insulation, the wrap, and the SEAI grant.
Common mix-ups
- "House wrap grant". There's no grant for a membrane. The grant people mean is SEAI's external wall insulation grant.
- "Wrap" on a timber frame house. A new timber frame has a breather membrane already. Insulating an existing timber frame from outside is a specialist job: ask the contractor how the system handles moisture.
- Roof membranes. Breathable roofing underlays are a related product used under tiles and slates. They're not part of a wall insulation grant either.
If you meant the wrap
SEAI pays €8,000 for a detached house, €6,000 for a semi-D or end of terrace, €3,500 for a mid-terrace and €3,000 for an apartment towards external wall insulation (seai.ie wall insulation page, checked 28 October 2026). Use the grant check on this page to see yours, or read the grant guide and the cost guide.
We don't sell breather membranes. For membrane products and specifications, talk to a builders' merchant or your designer.
Questions people ask
What is house wrap in building?
In the building trade, a breathable membrane wrapped around a timber frame or behind cladding to keep out wind and rain while letting vapour escape.
Is a breather membrane insulation?
No. It protects the wall from weather. It doesn't insulate on its own.
What does house wrap mean in Ireland?
Most people mean external wall insulation. SEAI names the measure "External wall insulation (the wrap)" and grants it.
Is there a grant for a breather membrane?
No. SEAI grants are for insulation measures like external wall insulation, not for membranes on their own.
See your grant, then get a price
Three taps show the SEAI grant for your home. Or call 087 162 1846 between 8am and 8pm and we pass you to one SEAI-registered external insulation contractor who covers your area.