Closed cell spray foam is the harder of the two to remove. It cures to roughly 40-50 kg/m³, bonds to timber like a structural adhesive, and has to be cut or ground out in slices rather than pulled away in sheets. Open cell is softer, lighter at around 7-9 kg/m³, and usually comes off in large chunks once you break the bond at the edges.
That single difference drives everything else - the tools we use, the time on site, the mess, and the price. Below we break down how each foam behaves in Lancaster lofts, roofs and cavity walls, what removal costs in 2026, and when it is worth getting our team in rather than tackling it yourself.
The short answer: closed cell is harder to remove
Open cell vs closed cell spray foam removal in Lancaster, Lancashire comes down to density and adhesion. Closed cell is dense, semi-rigid and sticks hard to rafters, sarking boards and masonry. Open cell is spongy, friable and tears away with far less resistance.
In practice, a typical 40 m² loft floor covered in open cell might take our team half a day to clear. The same area in closed cell - especially where it has been sprayed directly onto the underside of roof timbers - can run to a day and a half, sometimes two, with two technicians on site.
If you are weighing up Spray foam removal for a property you have just bought, the type of foam is the first thing we check. It changes the quote more than the size of the loft does.
What open cell and closed cell actually are
Open cell spray foam is a low-density polyurethane insulation that expands 100:1 or more when sprayed, filling every gap it touches. Its cells are broken, so air moves through it and moisture can pass in and out. It is soft enough to compress between your fingers.
Closed cell spray foam is a high-density polyurethane with intact, gas-filled cells. It expands around 30:1, cures rigid, and acts as a combined insulator, vapour barrier and - in some roof assemblies - a structural stiffener. It feels like dense polystyrene and does not compress easily.
Both were installed heavily across Lancaster between roughly 2010 and 2018, often under the Green Deal or through loft conversion firms. We find open cell most often in lofts and between joists. Closed cell turns up on roof decks, in dormer cheeks, and sprayed onto the back of slates in older stone-built terraces around Lancaster City Centre Spray foam removal where the roof void is tight.
Why closed cell fights you every step of the way
Closed cell spray foam removal in Lancaster is harder for four concrete reasons:
- Density. At 40-50 kg/m³ it resists hand tools. A standard scraper just skates off the surface.
- Adhesion. It bonds at 100 kPa or more to timber and masonry. On rafters it is effectively glued in place.
- Rigidity. It does not flex, so you cannot peel it. You have to cut it into blocks or grind it down.
- Vapour sealing. Because it seals the assembly, any trapped moisture behind it has nowhere to go - which is often why it needs removing in the first place.
Open cell, by contrast, is friable. Once you get a pry bar under an edge, big sections break away. It is dusty and unpleasant, but it moves.
We use different kit for each. Open cell comes out with oscillating saws, pry bars and a high-volume vacuum. Closed cell needs reciprocating saws with coarse blades, angle grinders with wire cups, and in some roof spaces dry ice blasting spray foam removal Lancaster to freeze and crack the bond without gouging the timber underneath.
How we remove each type in Lancaster homes
Our process starts the same way for both: an insulation assessment Lancaster to identify the foam type, thickness, coverage and whether the roof or loft has suffered any moisture damage. That survey tells us which removal method will work and what it will cost.
Open cell removal
- Seal the room and set up negative-pressure extraction.
- Cut the foam into manageable blocks with an oscillating saw.
- Pry sections off the joists or rafters.
- Vacuum every surface, then inspect the timber for damp or rot.
Most open cell lofts are clear in 4-6 hours for a two-person crew.
Closed cell removal
- Seal and extract as above, but with heavier filtration.
- Score the foam into 300-400 mm squares with a reciprocating saw.
- Grind or blast the residual layer off the timber.
- Sand or wire-brush the last film, then treat and dry the substrate.
A closed cell roof deck of the same area typically takes 10-16 hours. That gap in labour is the single biggest reason the two jobs are priced differently.
Open cell vs closed cell spray foam removal cost in Lancaster
Typical 2026 pricing in this area runs from £35 to £55 per m² for open cell and £55 to £85 per m² for closed cell. The premium reflects the extra labour, the heavier tooling and the longer disposal time.
For a standard 40 m² Lancaster loft, that works out roughly as:
- Open cell: £1,400-£2,200
- Closed cell: £2,200-£3,400
Roof deck removal sits at the top of those ranges because access is harder and the foam is usually thicker. Cavity wall extraction is priced per elevation rather than per square metre. If you want a firm number, we quote after the survey - no estimates over the phone, no surprises on the day.
One thing worth knowing: if your mortgage lender has flagged the foam, the removal report we produce is often accepted directly. We handle mortgage lender spray foam removal Lancaster jobs every month for buyers who need the roof cleared before completion.
Which is harder to remove open cell or closed cell spray foam in Lancaster?
Closed cell is harder. It is denser, bonds more aggressively and cannot be peeled - it has to be cut and ground out. Open cell is messy but cooperative, and it comes away in chunks once you break the edge bond.
That does not mean open cell is easy. Both types produce fine dust that needs proper extraction, both can hide damp timber underneath, and both need the substrate cleaned back to bare wood before any new insulation goes in. The difference is time on site, and time is money.
We have cleared both types from stone-built terraces in Marsh Spray foam removal and from larger detached homes in Haverbreaks Spray foam removal. The pattern holds: closed cell always takes longer.
Common mistakes we see on DIY removal jobs
We get called to fix DIY removal attempts most weeks. The same problems come up again and again.
- Pulling closed cell instead of cutting it. This tears splinters out of the rafter and weakens the roof structure.
- No extraction. Foam dust is a respiratory irritant. A shop vac and an open window is not enough.
- Leaving residue. A thin film of closed cell left on timber will stop any new insulation bonding properly.
- Ignoring the moisture. If the foam was hiding a leak, removing it just exposes the problem - fix the leak first.
- Skipping the disposal paperwork. Polyurethane foam waste has to go to a licensed facility. Fly-tipping it is a fine.
If you are part-way through and it has gone wrong, stop. We would rather survey it and finish the job properly than have you damage the roof further.
When to call a professional
Call us when the foam is closed cell, when it is on a roof deck, when the loft is small or awkward, or when a lender or surveyor needs a documented removal. Those are the jobs where DIY goes wrong.
Our team at Spray Foam Removal Lancaster handles both foam types across the district, including same day Spray foam removal Lancaster for urgent cases where a surveyor is due or a completion date is looming. We survey, quote, remove and clean up - you get the loft back.
Frequently Asked Questions
Which is harder to remove open cell or closed cell spray foam in Lancaster?
Closed cell is harder. It cures at 40-50 kg/m³ and bonds tightly to timber, so it must be cut and ground out rather than peeled. Open cell is lighter and friable, and typically comes away in chunks. Expect closed cell jobs to take roughly twice as long on site.
How much does open cell vs closed cell spray foam removal cost in Lancaster?
In 2026, open cell removal runs £35-£55 per m² and closed cell £55-£85 per m². A 40 m² loft is roughly £1,400-£2,200 for open cell and £2,200-£3,400 for closed cell. Roof decks sit at the top of those ranges.
Can you remove both open cell and closed cell spray foam in Lancaster, Lancashire?
Yes. We remove both types from lofts, roof decks, cavity walls and commercial buildings across Lancaster and the surrounding villages. The survey identifies which type you have and we quote accordingly, usually within 24 hours of the visit.
Does closed cell spray foam damage roof timbers when it is removed?
Not if it is cut out properly. Pulling it tears the timber surface. We score and slice it, then grind the residue back to bare wood, so the rafters stay sound. Any pre-existing rot or damp is flagged in the survey report.
How long does removal take?
A 40 m² open cell loft takes 4-6 hours with a two-person crew. The same area in closed cell takes 10-16 hours. Roof deck work adds time for access and safe working at height.
Get help with Spray foam removal in Lancaster
Whether you are dealing with soft open cell in a loft or hard closed cell on a roof deck, we will tell you exactly what is involved and what it costs before we start.
Call Spray Foam Removal Lancaster on 03335672543 to book a survey.