Cold Garages and Draughty Outbuildings: Why They Don’t Have to Stay That Way

A garage in Leeds sits at more or less the same temperature as the street outside it, because most were never built with insulation in mind — single-skin blockwork, an up-and-over door with no seal, and a roof that vents heat as fast as any heater can produce it. Same story with outbuildings: timber sheds, brick workshops, converted stables. If you’re using the space for anything other than storing a bike, that cold is a daily nuisance.

This service sits under our wider Spray Foam Insulation Leeds work, but garages and outbuildings have their own set of problems — condensation on tools, damp creeping into stored furniture, gyms and home offices that need a heater running constantly to stay usable. We treat them as a separate job with their own specification, not a smaller version of a loft.

What’s Actually Involved

Garage and outbuilding insulation usually means spraying closed cell polyurethane foam directly onto the underside of the roof and, where needed, the internal face of the walls. The foam expands on contact, fills every gap around rafters and blockwork joints, and sets rigid within seconds. Unlike a loft, there’s often no ventilation gap to worry about because a garage roof isn’t cold-side insulated in the same way a house roof is — the whole structure becomes part of the heated envelope.

For flat-roofed garages, which make up a fair number of the older ones in Leeds, we spray between and over the joists, closing off the thermal bridges that timber joists normally create. For pitched roofs matching the house, we follow the rafter line. Walls get sprayed where the garage is going to be used as living space — a gym, workshop, or office — rather than just for parking a car, since block walls lose heat as fast as an uninsulated roof does.

We also seal around the garage door frame, service pipes, and any airbricks that aren’t needed once the space is insulated. Airbricks left open after spraying just reintroduce the draught you’ve paid to remove.

Who This Actually Helps

Home gyms and offices. The single biggest driver of enquiries. Once you’re spending an hour a day in a converted garage, the cost of heating an uninsulated shell becomes obvious fast.

Workshops and hobby spaces. Woodworking, mechanics, model-making — anything involving glue, paint, or machinery that doesn’t like damp or cold performs better in a stable environment.

Garages used for storage of anything valuable. Tools rust, cardboard boxes take on damp, and paper — documents, books — degrades in fluctuating humidity. Insulation and a sealed structure slow that right down.

Outbuildings being converted for occupancy. Garden rooms, annexes, teenagers’ dens. If Building Regulations apply to the conversion, insulation levels are usually part of what’s checked off.

Landlords with outbuildings on rented properties. A garage that’s damp or unusable doesn’t help a let, and tenants notice.

From Survey to Finished Job

1. Free survey. We look at the structure — flat or pitched roof, block or timber walls, existing ventilation, any damp already present — and measure up.
2. Written quote. Fixed price, covering roof, walls if needed, and any sealing work around doors and vents. No surprises added on site.
3. Preparation. We clear obstructions, protect anything left in the garage, and check electrics and any existing damp aren’t going to be sprayed over and hidden.
4. Spraying. Closed cell foam applied to roof and walls as agreed. Most single garages take half a day; larger workshops or double garages a full day.
5. Trim and finish. Excess foam trimmed back to a clean, even surface. If you want plasterboard over the top for a finished look, we can arrange that or leave it foam-finished, which is common in workshops.
6. Sign-off. You get a completion certificate and paperwork confirming BBA approved product and the 25 year guarantee.

What You Get Out Of It

A garage or outbuilding insulated with closed cell foam holds heat instead of shedding it, which matters if you’re running any kind of heater in there — the running cost drops noticeably once the structure stops working against you. It also stiffens flat roofs and stops cold bridging at the joists, which is where a lot of garage condensation actually starts. Sealing the structure properly reduces damp risk for anything stored inside, and if the space is being converted for regular use, a properly insulated shell is part of what makes that conversion worth doing at all.

There’s a property value angle too. A usable garage-gym or garden office adds more to a house than a cold, damp storage box ever will, and it’s the kind of improvement a buyer notices when they open the door during a viewing.

Cost, Timescale and What the Survey Covers

Pricing depends on roof shape, whether walls are included, and the size of the structure. As a rough guide:

• Single garage, roof only: £600–£1,000
• Single garage, roof and walls: £1,000–£1,600
• Double garage or larger workshop: £1,600–£2,800
• Small outbuilding or garden room: £500–£1,200 depending on size and finish

Most jobs are completed in a day. Larger conversions with wall spraying and trimming can run to two days. The free survey takes about 30–45 minutes on site — we check roof structure, existing insulation if any, damp history, ventilation, and what the space is being used for, since that changes the specification. You get a written quote on the spot or within 24 hours, with no obligation to proceed.

Book a Free Survey

If your garage or outbuilding is costing you comfort, storage, or a usable room, a free survey will tell you exactly what’s needed and what it costs — no pressure, no obligation. We’re a Leeds firm based at Unit 9, Admiral’s Yard, Low Road, Hunslet, LS10 1AE, open 9am to 7pm, seven days a week. Call 0113 365 1084 or book online, and if the job doesn’t actually need doing, we’ll tell you that too.