You’ve been searching for the perfect garden room, and you’ve seen loads of options, but you need something that you KNOW is going to last. Guarantees vary wildly across the garden room market: some are comprehensive, some cover only parts of the build, and some don’t exist at all…
At Gillies & Mackay, we’ve been making timber buildings and putting them up all over Scotland for nearly 40 years. Our 30-Year Guarantee isn’t a clever bit of marketing; it’s a mindset and belief in longevity that’s at the heart of everything we do here. Every garden room is built with longevity and our legacy in mind, which is why we proudly offer a 30-Year Guarantee on every build.
But if you’re still feeling a little sceptical about how a 30-Year Guarantee is actually possible, or how it works, this blog post explains it all.
How long have G&M been in business?
Gillies & Mackay have officially been in business since 1989. There are even some buildings that predate this, like our wee natty shed that’s in our Show Area. We reckon this Shed is around 40 years old, and it’s still standing strong (though it could do with a fresh coat of paint).
Our founders, Grant Gillies and John Mackay, built G&M on a simple idea: that things should be built properly and to last, or not at all. Grant’s clever constructions are what make sure our buildings perform in the Scottish climate and John’s demand for quality is what shaped the G&M Standard, and still influences how every piece of timber is chosen today. Their attitude towards quality and craftsmanship has been instilled into everything we do at G&M ever since.
Why is longevity important at G&M?
As a family business that spans three generations, our legacy really matters to us (I’m Gen 3 by the way). We’re not building things to last a season or two, we’re building garden rooms we’d be proud to see standing in 50 years.
That standard follows through into how each Radiata Garden Room is actually made. Every one is built here at our workshop in Errol. Our team cuts the timber, makes the panels, crafts the finishings, then loads the vans, and delivers and assembles each one on site. This gives us full control over quality and finish. Each Radiata is made to the G&M Standard, from the timber selection itself – under the watchful eyes of Gordon and Bobbie – down to the final finish onsite, completed by perfectionists Dean and Arran. We know exactly what we’re putting out into the world, and know it’s built to last.
We’ve seen firsthand how our materials and construction methods hold up against the Scottish weather. Even though our Radiatas are a newer building (practically toddlers) they’re built with those same tried and tested methods, and to the same quality. That’s never changed. There’s 37 years of experience behind every Radiata, and it’s exactly why we can offer a 30-Year Guarantee.
What’s covered in our 30-Year Guarantee?
Our Guarantee is valid for 30 years from the delivery date of your Radiata Garden Room. Our Guarantee covers defects in materials and workmanship. A material defect would be something like a Radiata board splitting, and in that case we’d come out and replace it. An example of a workmanship defect would be if the Radiata boards hadn’t been installed properly, and that would be rectified too.
Our 30-Year Guarantee doesn’t cover damage due to improper use, unauthorised alterations, natural disasters, normal wear and tear, natural fading of materials, or superficial damage. An unauthorised alteration would be something like adding your own extension onto the building. Because this changes the structure beyond what we originally built and guaranteed, the guarantee would be invalid.
Natural fading of materials is a good example of something that may look like a defect but is completely normal. The outer Radiata cladding naturally weathers over time, changing from dark brown to blond, and eventually to silver. This is a natural timber process caused by UV and exposure to the elements, rather than a fault.
For our 30-Year Guarantee to be valid you do need to follow some simple aftercare advice. Our Aftercare Guide covers things like ventilation, cleaning out gutters and what to avoid for good timber care. Spoiler alert: you can’t clean your building with a power washer. But overall the Radiatas are pretty low-maintenance thanks to their impressive cladding.
For detailed instructions on how to look after a Radiata Garden Room, check out the full guide here.
What materials make our 30-Year Guarantee possible?
When we designed our Radiata Garden Rooms we chose materials that would perform in the Scottish climate and last for decades.
Radiata Pine ThermoWood
Radiata Pine ThermoWood is thermally treated with the ThermoWood process, which protects it against insects, rot and decay without needing any additional coating. The treatment also makes the timber very resistant to shape changes and moisture, so boards stay solid and true over time. Radiata Pine ThermoWood has a 50 year life expectancy, so we can rely on it to last well beyond our guarantee. It’ll be the only thing left with the cockroaches when the world implodes.
Aluminium double-glazing
Radiata Garden Rooms feature aluminium double-glazed windows and French doors. These frames outperform timber framed windows and even uPVC in terms of durability. Aluminium won’t warp or move the way timber frames can, and its strength means it holds up well against the wet and unpredictable Scottish climate.
Isola shingles & steel box profile roofing
Our Radiata Garden Rooms feature Isola shingles, or steel box profile roofing depending on what model you go for. Our Nova Mica steel box profile roofing has an impressive 20-year manufacturers guarantee. Steel box profile handles strong winds and rainfall exceptionally well. While Isola shingles carry a 30-year manufacturer’s guarantee and are highly resistant to weather and moisture.
4-layer wall
Our 4-Layer wall is what keeps a Radiata insulated and watertight. This is a must for a garden room to survive in Scotland. It combines 50mm foilback rigid board insulation with a 20mm air cavity, eliminating the cold spots where moisture would otherwise collect and rot timber from the inside. This is what keeps the interior completely dry over time.
The frame itself uses 45mm x 75mm pressure-treated C24-graded timber. This means it’s quality-checked for strength and density, giving the structure the load-bearing capacity to stay solid for decades.
Further Reading: What’s the best specification for a small garden room?
Why does the base matter for our 30-Year Guarantee?
Just like the materials, what a Radiata sits on matters as much to its longevity. Every Radiata needs a level, slabbed base to properly support it. Without that, even the finest materials in the land won’t hold up.
We project-manage each Radiata build, which includes creating a base plan and ensuring that each base is to standard. We’re strict about bases; we’ve even had contractors occasionally tell us we’re going overboard. But if we’re guaranteeing a building for 30 years, it needs a base that can hold it up for its entire lifetime.
A solid, level foundation is what keeps your garden room square throughout the years. If a base isn’t right, the building shifts, creating gaps in the cladding, or causing windows and doors to sit out of square and let water in around the edges. Basically, once the building is out of square, everything falls apart. That kind of movement is exactly what shortens a garden room’s life.
Grant decides exactly what base each build needs, whether it’s a standard slabbed base, or upgraded to a full concrete base, depending on the size and weight of the structure. Getting that decision right at the start is what lets us stand behind the building for the next 30+ years.
Why is aftercare important for our 30-Year Guarantee?
Another reason we can offer a 30-Year Guarantee is that every Radiata comes with detailed aftercare advice. This covers everything from cleaning and ventilation to cladding and laminate care, so you’re never left guessing.
Maintenance requirements are minimal. But with our guide, you’re set up to look after your garden room properly from day one.
This advice isn’t guesswork on our end, either. It’s built on 37 years of experience looking after timber in the Scottish climate. As we learn more, Amy and I update that advice so it always reflects what actually works. And if a question ever comes up that we haven’t covered, we’re always on hand to help. We’d love to hear something we hadn’t thought of. This solid advice, backed by real experience, is what assures us that we’ve done our due diligence, educating our customers so they know exactly how to look after their garden room.
How does the guarantee process work?
Our guarantee process is simple. If anything does go wrong with your garden room, just get in touch — by phone, email, or in person — and let us know what’s happened. We’ll usually ask for a few photos, and a description of the problem. This lets us identify the issue and work out the best course of action. Once we’ve got a plan, we’ll be in touch (usually by email). Then we’ll arrange a date for one of our team to visit your property. Our team will arrive at your house and rectify the issue on the building. This is usually completed in a single visit. Job done!
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How does the G&M guarantee compare to other garden room companies?
The standard guarantee across the garden room industry is around 10 years. But not all guarantees are created equal. A lot of companies advertise a guarantee period on their website with no further detail beyond the actual number. Very helpful. I’d always urge you to ask for the full guarantee conditions before you buy a garden room. That way you know exactly what you’re getting.
Let’s take a look at some real examples to see how they measure up.
JML Garden Rooms
JML Garden Rooms offer a 10-year structural guarantee on each of their garden rooms. They don’t publish any further conditions on their website, but a structural guarantee typically implies cover for structural elements. This would include things like framing and wall and roof panels, rather than cosmetic elements like cladding finish.
Outside In Garden Rooms
Outside In Garden Rooms have a 10-year insurance-backed guarantee on the entire build. This is stated in the FAQ section of their website, though without the full terms published with it. An insurance-backed guarantee means that even if Outside In stops trading, customers could still claim. The insurance provider would pay for repairs in line with what was originally promised. This gives customers reassurance that they’ll always be covered, which is especially important for a newer garden room company.
Tiger Sheds
Tiger Sheds, a large timber garden buildings supplier, offers a 20-year guarantee. This looks great at first glance but it’s not the full story. The 20-year guarantee that is advertised on their website specifically covers rot and decay in pressure-treated timber. Most pressure-treated timber carries a 20-year guarantee, because this is the guarantee of the pressure-treatment process itself. If something goes wrong with a Tiger Sheds garden room that isn’t related to rot in the timber, like if the timber boards warped, this would not be covered in the guarantee.
This is why it’s important to check the guarantee conditions before you buy. A headline number like 20 years can sound reassuring, but doesn’t tell you much until you know what it covers.
As far as we’re aware, we’ve not seen any garden room companies in Scotland offering a guarantee as significant as ours, both in length and in how much of the build it actually covers. We would love to have some company though.
How do we offer a 30-Year Guarantee on our Garden Rooms?
Our 30-Year Guarantee isn’t something we offered in our first year of business back in 1989. It’s been earned over decades of experience, watching how our buildings actually hold up against the Scottish weather.
We have complete confidence in our Radiata Garden Rooms because we know they’re built to last at every stage — from the materials we choose, to getting the base right, to the aftercare that keeps it performing for years to come.
If you want a garden room that’s going to be with you through decades of your life, without the worry of what happens if something goes wrong, a Radiata Garden Room is exactly what you need.
If you’re excited about the long-term durability of a Radiata Garden Room and want to know what happens next, check out our Prep Guide here.
