The Window Reveal Is a Radiator

The wall is done. The WhatsApp photograph is a cream coat from the eaves to the damp-proof course, and someone in the group chat has written “fair play”. Every window is still a picture frame of cold.

A reveal is not a decoration. A reveal is the masonry return around the glass — the jambs, the lintel, the cill — plastered like a polite picture frame. Insulate the field of the wall and leave that frame as dense block, and you have bought a coat with no cuffs. Heat does not applaud the coat. Heat walks around the wrist.

The hole in the wall has a picture frame

Let us invent a person. We will call her Sinéad. 1978 semi, Terenure. Yellow brick, a cavity filled in 2014, later a cream wrap. The bedroom is “grand now” except for the black stripe in the top corner of every window, the one she wipes in March and that comes back in November like a subscription.

The wall, as a field, is fine. That is the insult. Put a hand on the plaster a metre from the glass and it is ordinary. Put a hand on the plaster that turns the corner towards the frame and it is a radiator in reverse: a strip of masonry dumping heat into the weather and dumping cold into the room. The window gets the blame. The window is glass in a hole. The picture frame was never in the quote.

Heat walks around the coat

Insulation is a fence. Heat is a toddler. The toddler does not argue with the fence. The toddler walks to the gate. The gate, on a Dublin elevation, is every opening. Eight windows. Each one is four sides of masonry that never got a fence.

U-value is the score for the field: how easily heat walks through a square metre of wall. Psi-value is the score for the line: how easily heat walks along the junction. A beautiful U-value with a rude psi-value is a jumper with the cuffs cut off. You will still be cold at the wrists.

Researchers at UCL spent a paper on this and found the unromantic thing: at the junctions of an insulated wall, most of the heat flux is at the reveals. They were looking at internal lining. The toddler does not care which side of the wall the fence is on. Leave the picture frames uninsulated and the house keeps a set of radiators it cannot turn off.

This is not a wet cavity, slumped beads, or an air brick stuffed with newspaper. Those are other holes. This hole is dry, filled or wrapped, photographically complete, and still a radiator at every pane.

Two jobs, same missing cuff

There are two costumes in Dublin, and they fail the same exam.

Costume one: cavity fill. Two leaves, a gap, a hopper, a weather of beads. The gap is the job. The reveal is not the gap. The reveal is the inner leaf turning the corner to meet the frame, often with a closer that is a strip of plastic, a bit of board, or a rumour. Fill the gap and the field improves. The picture frame is still dense block, plastered, conducting around the beads. A cavity closer can be an insulated closer. A lot of them are not.

Costume two: the wrap. Boards on the outer face. Render. A cream house. External wall insulation Dublin as a weather coat, not a paint job. The coat is correct for the field. The coat is a lie at the opening if the boards stop at the window like sleeves that end at the elbow. The 2021 Acceptable Construction Details for external wall insulation draw the cuff: insulation returned into the reveal, overlapping the frame. Jobs skip it because the frame is tight and “sure it’s only a hundred millimetres of block.” A hundred millimetres of block around eight windows is a lot of radiator.

The second-wall ticket in 2026 is how a 2014 hopper and a 2026 wrap end up on the same house. If you already used the cavity grant, you can still talk about a wrap. The wrap is not a spell that makes the reveals disappear. Draw the picture frames or you own two certificates and the same black stripe.

The black corner is physics

Mould is not a lifestyle. Mould is a surface that got cold enough, long enough, in a room that makes water the way people make water: showers, kettles, sleeping. The field of an insulated wall stays above the trouble. The uninsulated reveal drops. Indoor air hits the plaster return, drops its drink, and the top corners of the window start a hobby.

Sinéad wipes. She replaces the window because a man said the glass was the problem. The new window sits in the same masonry picture frame. The stripe takes a month off and comes back. The wall is still “done”. The cuff is still missing.

You can feel it without a camera. The plaster a hand’s width from the glass is a different temperature to the plaster in the middle of the wall. That difference is the quote that stopped at the wrist.

What the camera is looking for

You cannot diagnose a reveal from the footpath. The cream coat looks finished. Finished is a paint word.

A surveyor looks at the return. Is there insulation meeting the frame, or is there plaster on cold block? On a wrap: do the boards turn the corner, and is the new cill deep enough that the coat is not sitting on a strip of bare masonry under the glass? On a cavity: is there an insulated closer, or a plastic trinket, or a gap the beads were supposed to “sort”? A thermal camera is a toddler-detector: the field is dark, every opening a glowing rectangle. A borescope at the jamb is a grown-up sentence. Guessing is how the picture frame survived two grants.

The live piece on the air brick that is not a letterbox is a different hole: a honeycomb someone painted shut because it looked like post. Do not confuse a blocked nose with a missing cuff. One makes a pond in the wall. The other makes a radiator around the glass. They are not the same job.

If the person quoting you will not look at the reveals, they are quoting a field. A field is not a house. A house is a field plus every gate.

The money, without folklore

These are the current individual-grant figures, taken from SEAI’s own wall page. They are fixed by house type, not a percentage of a quote, and they are not a prize for wrapping a field and leaving a radiator at every pane.

Cavity wall insulation, standard: apartment €700, mid-terrace €850, semi-detached or end-of-terrace €1,300, detached €1,800. That money is for a cavity that deserves a fill: clean, dry, empty. It is not a bounty for pumping the gap and ignoring the picture frames. Higher cavity figures exist if you are on a qualifying welfare payment: apartment €900, mid-terrace €1,100, semi-detached or end-of-terrace €1,700, detached €2,300.

The wrap is €3,000 for an apartment, €3,500 for a mid-terrace, €6,000 for a semi-detached or end-of-terrace, and €8,000 for a detached house. Internal lining is €1,500 / €2,000 / €3,500 / €4,500 across those same four types. The official wall numbers live on the SEAI wall insulation grant page. The plain-English table, edited 28 May 2026, lives on the Citizens Information page for Better Energy Homes.

Attic insulation is still the hat, and the hat still comes first. Standard: apartment €1,100, mid-terrace €1,400, semi-detached or end-of-terrace €1,500, detached €2,000. Enhanced, if you qualify: €1,400 / €1,800 / €1,900 / €2,500. What you pay after the grant, on a normal Dublin attic done properly, is typically €300 to €1,500. Do the hat. Then argue about the walls, including the cuffs.

The house has to have been built and occupied before 2011. Approval comes before work. If work starts before SEAI says yes, the grant is gone. If SEAI does not approve, no work starts, and you pay nothing. That is the grant guarantee as Retrofit Dublin runs it. Retrofit Dublin is SEAI-registered. The phone is 01-233-7477. The 15-year guarantee is on the insulation, not on the folklore that a cream elevation is a finished junction.

Technical Guidance Document L is the energy rulebook: U-values for the field, and Appendix D for the lines, because a wall is not only a wall. A default y-value of 0.15 is the polite way of saying “we did not draw the junctions.” 0.08 is the number you get when the junctions look like the drawings. Reveals are in the drawings. The Irish Times set out the 2026 second-wall change when the package landed. RTé put the insulation-grant increases in the same January announcement. Neither of them is going to write you a hymn about a plastered reveal. That is our job.

Insulate the cuffs, then argue about the coat

A whole-home energy strategy is an order of operations. You stop the leaks. Then you change how you make the heat. The cheapest first move in most Dublin houses is still the hat. Then the walls — all of them — including the picture frames around the glass. External cavity if the camera says the gap is clean, dry, empty, and the closers are not a rumour. A wrap if the cavity is the wrong job, with the boards returned into every reveal so the coat has cuffs. Then the machines.

Retrofit Dublin does home energy upgrades in that order on purpose: fabric, then systems. A heat pump behind a cream wall and a set of uninsulated reveals is a very efficient device heating the picture frames. Do not buy an expensive machine to feed a cuff you refused to draw.

You can keep the quote that treated the windows as someone else’s invoice. It is a historical document of optimism. The field can be fine. The plastered return can still be a radiator. Do the hat. Look at the reveals. Return the insulation to the frame. Apply before anyone drills. If SEAI does not approve, no work starts, pay nothing. Phone 01-233-7477.

If the window reveal is still a radiator and the cream coat still ends at the wrist, call 01-233-7477 and Claim Your Grants.