Mr Mastic · South East, London and Scotland
New-build mastic and snagging
Second-fix and plot mastic for developers, and snagging failed builder sealant for new-home owners.
- Shower seals failing in the first year or two
- Sealant applied over dusty or wet surfaces
- Gaps opening as the house dries out and settles
What new-build mastic & snagging involves
New homes move as they dry out and settle, and sealant applied in a hurry at handover often fails in the first year or two. We reseal snagged bathrooms, kitchens, windows and floors for new-home owners, and carry out plot mastic for builders and developers.
We work across the South East, London and all of Scotland from our base in Crawley. Every job comes with our one-year guarantee, and we’re fully insured and an ARBOMaster approved applicator.
Problems we put right
- Shower seals failing in the first year or two
- Sealant applied over dusty or wet surfaces
- Gaps opening as the house dries out and settles
- Untidy sealant flagged on a snagging list
- Developer sealant that never fully bonded
Where we work
- Bathrooms & en suites
- Kitchens
- Windows & doors
- Skirting & floors
- Plot handovers
- Show homes
How it works
- We go through the snagging list or plot schedule and agree the joints to do.
- Failed or untidy sealant is cut out completely.
- Surfaces are cleaned and primed where needed, removing dust left from the build.
- New sealant suited to each joint is applied and tooled neatly.
- Each area is checked and left with its cure time.
A real example
At a Forge Wood new build in Crawley, the shower tray seal had failed after 16 months. The builder’s sealant had gone onto a gritty, unprimed surface. We took it all out, primed the surfaces and resealed with sanitary silicone.
Your developer’s warranty
If your home is still within the builder’s snagging period, report problems to them first. If they’re slow or the work keeps failing, we can help.
A real job
At a Forge Wood new build in Crawley, the shower tray seal had failed after 16 months. The builder’s sealant had gone onto a gritty, unprimed surface. We removed it all, primed the surfaces and resealed with sanitary silicone.
Why it’s worth doing now
New homes move as they dry out and settle, and the sealant laid at handover often can’t cope. Small gaps in a shower or along a bath can let water reach floors and ceilings that are only a year or two old, so they’re worth putting right early.
What affects the quote
We don’t publish set prices, because every job is different. Call or email us with a few details and we’ll give you a clear quote before we start. The main things that affect it are:
- How many joints, rooms, windows or metres of joint there are
- How much old sealant or grout has to come out, and how many layers
- Mould, damage or movement that needs dealing with first
- Access: stairs, height, ladders or work outside
- The product the joint needs (sanitary, exterior, fire-rated, glazing or sand mastic)
- For commercial sites, working hours and phasing
What a good quote includes
- All the old sealant removed, not sealed over
- The product named for each joint
- How long the guarantee is and what it covers
- How long before the area can be used
- How your home or building will be protected
- Who is doing the work, and that they’re insured
Aftercare
Keep your snagging list up to date and report sealant failures to your developer while you’re within their snagging period. After a reseal, give the joints the cure time we give you before they get wet.
What customers say
Rated 4.9 on Google from 180+ five-star reviews. Read the reviews on Google.
“Called for a bathroom reseal and the mastic man showed up on time with all the right equipment. Brilliant attention to detail. The sealant looks perfect and they kept everything tidy.”
“We had old mastic that needed replacing throughout our kitchen and bathrooms. The mastic man professional was knowledgeable, quoted fairly, and delivered excellent quality work. Highly recommend!”
“Professional mastic man service from start to finish. They assessed the work properly, gave a clear quote, and executed the job perfectly. Very satisfied with the results.”
New-build mastic and snagging: common questions
Why does sealant fail so quickly in new builds?
The house dries out and moves in its first couple of years, and sealant is often applied quickly onto dusty surfaces. Both lead to early failure.
Do you work for developers?
Yes. We carry out plot mastic and second-fix sealing. Send us the plot schedule and we’ll quote.
Should I wait before resealing?
If the seal has failed and water is getting in, don’t wait. Small gaps opening as the house settles can be resealed once movement has slowed.
Is the work guaranteed?
Yes. Every job comes with our one-year guarantee.
Do you give a price before you start?
Yes. Call or email us with a few details and we’ll give you a clear quote, so you know the price before any work starts.
Are you insured?
Yes. Mr Mastic is fully insured, and we’re an ARBOMaster approved applicator.
Page updated 26 October 2026
Near you
We cover the South East, London and Scotland. Find new-build mastic & snagging in your town:
- London
- Crawley
- Brighton
- Guildford
- Chelmsford
- Colchester
- Southampton
- Reading
- Oxford
- Edinburgh
- Glasgow
- Aberdeen
- Dundee