External Wall Insulation Systems
Complete, high-performance EWI systems that wrap your property in insulation — dramatically improving warmth, energy efficiency and weather protection.
Jersey's dedicated external wall insulation specialists. We transform homes and buildings with high-performance insulation systems and flawless silicone render finishes — warmer interiors, lower energy bills and standout kerb appeal, delivered start to finish.
We focus on one thing and do it exceptionally well. As Jersey's external wall insulation specialists, we install complete EWI systems and finish them with high-quality silicone render — for private and commercial properties alike.
Complete, high-performance EWI systems that wrap your property in insulation — dramatically improving warmth, energy efficiency and weather protection.
A flawless, crack-resistant silicone render finish over your insulation — self-cleaning, breathable and available in a wide range of colours and textures.
Founded by Gary Mc Geoghegan in 2017, GMAC has become Jersey's dedicated external wall insulation specialist. We don't spread ourselves thin across every trade — external wall insulation and silicone render finishes are all we do, and we do them to an exceptional standard.
From tired, uninsulated walls to a warm, weatherproof and beautifully rendered exterior — see what a full external wall insulation system delivers. Drag the slider to reveal the transformation.
No vague timelines. No surprise costs. Every external wall insulation project moves through the same four stages, communicated clearly from day one.
We visit and survey your property, assess the walls, and recommend the right insulation system and render finish. No pressure, no obligation.
Clear, all-inclusive pricing in writing — materials, labour and timeline. Full transparency on every cost, with no surprises at the end.
Insulation boards fixed and reinforced, then finished with a high-quality silicone render — applied by our specialist team for a durable, weatherproof result.
A final inspection together. We keep the site tidy throughout and don't sign off until you're standing in front of it, delighted.
A selection of recent external wall insulation projects across Jersey — high-performance systems finished in silicone render. Real homes, real transformations.
External Wall Insulation
Silicone Render Finish
Insulation System
Render Detail
Completed Project
Finished Exterior
There are plenty of general builders in Jersey. Few are true external wall insulation specialists. With a wealth of experience — working locally, in the UK and Ireland — we focus on one thing and do it exceptionally well.
External wall insulation and silicone render are all we do. That focus means deeper expertise and a better, longer-lasting result.
A properly installed EWI system dramatically improves thermal performance — warmer rooms and noticeably lower energy bills.
We finish every system in high-quality silicone render — crack-resistant, self-cleaning and available in a wide range of colours.
Clear quotes, tidy sites and efficient project management. Your job is done on time and on budget, every time.
Don't take our word for it — our reviews speak for themselves. Real words from real Jersey homes and businesses we've worked with.
"GMAC are a very professional service. Clean workers, got the job done quickly with a great finish. I'll use them again and would highly recommend them too."
"I called Gary for a quote on a Wednesday afternoon and he was with me within a couple of hours. Arrived promptly the next day and the whole job was finished well within the promised timescale."
"Gary & his lads have done a fantastic job on our house, and we would certainly recommend GMAC to anyone."
"Great service as always. The job was done on time and to perfection, as you can see in the photos. Thanks GMAC."
"Gary is a little grafter and super reliable. We've used him numerous times now and will without doubt again in the future."
Your honest feedback helps other Jersey homeowners and businesses find an insulation specialist they can trust. It takes less than a minute.
Review on GoogleWe're growing, and we're looking for grafters who take pride in the finish — experienced hands and keen learners alike. We focus on one trade and do it exceptionally well, which means consistent work, real skills development and a finish you'll be proud to put your name on.
A full project pipeline across Jersey means consistent hours and reliable income — not stop-start contracting.
Learn external wall insulation systems and silicone rendering — in-demand specialist skills that set you apart.
Work directly with Gary and a small, skilled crew. No layers of management — just good people doing good work.
5-star rated by clients across the island. Join a team known for doing the job right, first time, every time.
Complete the short form with your details, the role you're after and a quick summary of your experience.
If it looks like a fit, Gary will call you for an informal chat about the role, rates and start dates.
Join the crew for a paid trial day so both sides can see it's the right fit — then we get you started.
Tell us about your property. We'll survey the walls, recommend the right insulation system, and give you a clear, all-inclusive quote in writing.