Ask three contractors to price “resealing the windows” on a commercial building and you may get three very different figures. Usually that isn’t because one of them is wrong. It is because each has made different assumptions about access, preparation, product and programme.
This guide explains the factors that drive the cost of commercial sealant work. It doesn’t give prices, because they depend on the details covered below. What it will do is help QSs, FMs and contractors write a clearer brief, spot the gaps in a quote, and understand why two similar-sounding jobs can cost quite differently.
Joint length and count
Length is the obvious starting point. Most sealant work is measured in linear metres, sometimes with item counts for things like penetrations, sanitaryware or frames.
But length alone misleads. A long, straight, easily reached facade joint can go quicker than a short run of fiddly joints around pipework and fittings. Many small, separate items take more time per metre than one continuous run. A good brief gives both lengths and a description of what the joints are like.
Access
Access is often the largest single variable. Joints reachable from the floor or from steps are quick to get to. Joints that need podiums, towers, mobile platforms or other equipment add set-up time, equipment hire and sometimes extra people.
- Where the joints are: ground level, upper floors, over roofs or atria.
- Whether existing scaffold or access from other trades can be shared.
- Ground conditions, landscaping or traffic that limit where equipment can go.
- Restricted areas that need escorts or permits.
If access is already arranged on site, say so in the brief.
Removing what’s already there
On resealing work, taking out the old sealant can take longer than putting the new in. It depends on:
- how much old sealant is present and how hard it has become
- whether there are several layers from past reseals
- how well it is stuck to the substrate
- whether mould or contamination needs treating
- how much cleaning the faces need to get back to sound material
In older buildings, there is also the asbestos question. If the register shows, or testing finds, asbestos in old mastic, that part of the work needs a specialist and the programme changes.
Joint condition and preparation
Some joints need more than a clean before sealing. Broken edges in floors, crumbling arrises in concrete, or a joint that was built too narrow for its movement all affect the scope.
A contractor who has seen photos or visited can tell you if the edges need repairing first, or if a joint design problem means a straight reseal won’t last. That advice may change the scope and the price, but it is better found at quote stage than halfway through.
Need the work done? Mastic Doctor covers South East England, London and all of Scotland, with a 12-month guarantee on our workmanship. Send details for a fixed quote.
The product specified
Different sealants cost different amounts, and some take longer to apply.
| Factor | Effect on cost |
|---|---|
| Generic type (silicone, PU, hybrid, polysulphide) | Material price varies by type and grade |
| Fire-rated or intumescent | Specialist products, installed strictly to tested details |
| Primer required | Extra material and an extra step |
| Coloured or colour-matched | Availability may limit product choice or need ordering |
| Backing rod or bond-breaker | Material and time in deep or wide joints |
| Joint size | Wider and deeper joints use more sealant per metre |
Where a specification names a product, price to that. Where it doesn’t, ask each contractor what they intend to use so quotes are comparable.
Phasing, hours and disruption
A building that can be handed over empty is the simplest case. Most commercial buildings can’t be. Cost rises when work has to be split into many short phases, fitted around trading or occupancy, or broken up by access restrictions.
Things that add time include washrooms that must be done one at a time, floor joints worked in small sections, and areas where cure time must pass before reopening. Weather matters for external work too, as cold, damp or frosty mornings can stop sealing. Tell contractors your site hours and access windows so they can plan and price for them realistically.
Location, logistics and paperwork
Getting to site and working there has its own cost. Central London loading and parking need planning. Remote Scottish sites involve travel. Large estates may need moving between buildings. Inductions, permits and escorts take time.
Paperwork matters as well. RAMS, insurance details, CSCS evidence and records such as photos or product data all take preparation. These are normal on commercial work, but the brief should say what is needed so every quote includes it.
Fire-rated work tends to need more detailed records than general sealing, such as the location of each seal and the tested detail followed. If you need that, say so at the start. Adding it after the work is done is much harder than building it into the method.
New-build packages versus maintenance work
The cost drivers shift depending on the type of job.
On new-build and refurbishment packages, joints are usually new, clean and accessible, and there is no old sealant to remove. The main factors become the specification, the programme, how many visits are needed as other trades finish, and snagging allowances. A package that has to follow the main contractor floor by floor costs differently from one done in a single run.
On maintenance work in occupied buildings, removal, preparation, phasing and access tend to dominate. Older buildings may bring asbestos checks and joint repairs. Multi-site programmes add travel and coordination but can save on mobilisation when sites are grouped. See our guide to planned sealant maintenance for how batching helps.
Comparing quotes fairly
When quotes differ, check what each one includes:
- removal of old sealant, or just new sealant
- preparation, primer and backing rod
- the product type and colour
- access equipment
- phasing and working hours
- records and paperwork
- guarantee terms on workmanship
A lower figure that leaves out preparation or access is not a saving. Mastic Doctor gives a fixed quote once we have details, photos, drawings or a site visit, and our work carries a 12-month guarantee. For commercial sealant contractors work, send details through our quote form or call for a quote.
Quick answers
Why don’t you publish prices?
Because access, removal, product, phasing and location change every job. A fixed quote based on your details is the only figure worth having.
Is sealant priced per metre?
Often, in linear metres, sometimes with item counts. Length alone doesn’t set the price; access, preparation and product matter as much.
What information helps get an accurate quote?
Photos, drawings or a joint schedule, rough lengths, access details, the specification, site hours, and any paperwork you need.
Why do two quotes for the same job differ so much?
Usually different assumptions about removal, preparation, access, product or phasing. Compare what each includes, not just the total.
Does colour-matched sealant change the cost?
It can, depending on which colours are available in the specified product. We’ll confirm the colours available with the quote.
Can a site visit change a quote based on photos?
Sometimes. Photos are often enough, but a visit can reveal access limits, joint damage or extra layers of old sealant that change the scope.
Related services
- Commercial sealant contractors
- Mastic sealing for building owners and managing agents
- Construction and new-build mastic
More advice
- How to Choose a Commercial Sealant Contractor
- Planned Sealant Maintenance for FMs
- How Long Does Commercial Sealant Last?
- Asbestos in Old Mastic: What Duty Holders Need
- All advice
This guide is general information about sealant work. It isn’t legal, fire-safety or structural advice; for those, speak to a qualified professional.