Buckinghamshire · England
Window Mastic in Grendon Underwood
Professional window mastic in and around Grendon Underwood, with old sealant always removed completely and a one-year guarantee.
- Gaps where the sill meets the wall
- Whistling draughts around closed windows
- Gaps between the frame and the inside reveal
About our window mastic in Grendon Underwood
Homes in Grendon Underwood have every kind of window: from uPVC casements to timber and aluminium, plus patio doors, French doors and sills. The sealant is chosen to suit the frame material and the wall. We’re often asked to deal with draughts coming in around windows and doors and untidy mastic left by window fitters, on composite doors, timber windows & doors and patio & French doors.
Somewhere as small as Grendon Underwood, older homes often have timber frames set in stone or brickwork. Older buildings like these don’t always suit modern silicone, and sometimes a traditional sand mastic is the better choice.
The work is covered for a year after we finish. If anything isn’t right with it, phone 0345 464 0079 or drop us an email.
- Location
- Grendon Underwood (HP18)
- Region
- Buckinghamshire
- Cover
- 12 months on all our work
- Price
- A clear quote up front
- Telephone
- 0345 464 0079
- Last updated
- 26 October 2026
When to call us in Grendon Underwood
Plenty of failed mastic was poorly applied in the first place. Sealant run over dust, wet brick or loose mortar never bonded as it should, and it lets go sooner than it should.
It’s worth asking for a quote if you see:
- Mastic that is falling out in pieces
- Untidy mastic left by window fitters
- Draughty joints inside around the window
- Hard, cracked sealant around windows
If you look after a building such as Grendon Underwood Combined School, its window and door frames need their mastic kept sound, just like a home’s.
Comparing quotes
- How much experience the applicator has
- Is the old sealant removed completely?
- What insurance they hold
- Whether you can choose the colour
Should I try it myself first?
A DIY attempt doesn’t rule out a professional job. We cut it out and start again.
Some jobs are best left to a professional: work at height, external movement joints, fire-rated sealant and large areas need the right product, the right access and the right method.
What the job involves on each surface
Aluminium frames
Aluminium needs a sealant that bonds to coated metal. Neutral-cure sealant is the safe choice.
Window sills
Sills catch the water running down the glass, so the joints at each end and underneath matter. Each is cleaned out and resealed.
Why it’s worth doing now in Grendon Underwood
Once mastic fails, rain can get between the frame and the wall. Over time that can mean damp patches, damaged plaster and rotting timber. Resealing now is a small job by comparison. Around Grendon Underwood, older homes often have timber in their floors and frames, and water through a failed joint can rot timber if it’s left.
The cost reflects the work involved, not guesswork. That’s why we ask a few questions first and send you a clear quote before any work starts.
What you get with us
- Trusted Arbo and Everbuild sealants
- Over 20 years’ experience
- We never seal over old sealant
- A sealant colour to suit the surroundings
When it is not the sealant
A few problems are outside what sealant work can do:
- Damp problems in the wall away from the window
- A sash or casement that will not close properly
- A door that needs adjusting, rehanging or new seals
If in doubt, phone 0345 464 0079 or drop us an email and we will say what we think.
Surfaces we seal
- Aluminium frames
- Composite doors
- Timber windows & doors
- Patio & French doors
- Window sills
- uPVC windows
How it works
Most of a good job is in the preparation, and we do not rush it. Every joint is cleaned and dried before new material goes in. All told, the work takes anything from an hour or two to a full day, depending on how many frames there are. In a small place like Grendon Underwood, access is generally the main thing to plan. For outside work, also let us know about exposed walls and any outbuildings involved.
- First, we confirm safe access to each frame.
- Old, cracked mastic is removed completely.
- Frame and wall are cleaned and must be dry before sealing.
- Backing rod fills deep voids and the sealant goes in on top.
- The joint is shaped to shed water and the area tidied.
How to prepare
- For indoor joints, keep the area dry beforehand if you can
- For business premises, tell us about site rules or sign-in
- Mention any leaks or damp you’ve noticed
Ask for a quote
Need a quote? Please call 0345 464 0079 or drop us an email and tell us about the job. You will know what we plan to do, and what it will cost, before any work begins.
Related advice
Common questions in Grendon Underwood
Is there a guarantee on window mastic in Grendon Underwood?
All our work, in Grendon Underwood and everywhere else, comes with a 12-month guarantee. We are fully insured, and an ARBOMaster approved applicator.
Do you cover Grendon Underwood for window mastic?
Yes, Grendon Underwood is within the area we cover. Our work covers London and the South East. You can phone 0345 464 0079 or send us an email and let us know what needs doing, and we will send you a clear quote.
Is there any odour?
Some sealants have a smell while they cure, which fades as it sets. Opening a window helps.
Do you hold any approvals?
Yes. We hold ARBOMaster approved applicator status.
Should I try DIY first?
That depends on the joint. High-level, external movement and fire-rated joints are professional jobs.
Do you work for landlords and businesses?
Yes, often. We can quote for several properties at once.
Can you match the sealant to my frames?
Yes, in most cases. Mention the frame colour when you ask for a quote and we will match it as closely as we can.
What sealant do you use?
Quality sealants from brands including Arbo and Everbuild, picked for each joint. We explain the product when we quote.
Places near Grendon Underwood
Other services in Grendon Underwood
For landlords and businesses
Mouldy or split sealant often shows up at the end of a tenancy, and it’s quick to put right between tenancies. We can quote for more than one property at once.
A neglected joint can let water reach the structure, which matters even more when someone else lives there. Resealing at the right time is simple maintenance.
Window mastic in Grendon Underwood: local notes
With historic houses such as Claydon House (about 3.6 miles north-east) nearby, there’s older building stock in the area around Grendon Underwood as well as newer homes. Where a home is older, older frames set in brick or stone need a sealant that suits them, and sometimes that is traditional sand mastic. Compared with the north and west, the South East gets less rain, but outside sealant still needs a dry, clean surface, so outdoor work is planned around the forecast.
If you live in an older home near Church of St Leonard, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
Grendon Underwood is about 6 miles east of Bicester, in Buckinghamshire. From the centre of Grendon Underwood to the outskirts, window mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Grendon Underwood is one of 263 places in Buckinghamshire where we work. There’s also a page for Oxford, roughly 13 miles from Grendon Underwood.
All of HP18 is within our area for window mastic. That includes homes and businesses on Main Street, The Firs and Darley's Close and the roads around them. We also cover the places around Grendon Underwood: Edgcott (1 mile north), Ludgershall (2 miles south-west), Piddington (3 miles south-west), Blackthorn (4 miles west) and Brill (5 miles south-west). Further out, we also cover Aylesbury (9 miles south-east), Buckingham (8 miles north), Elmhurst (9 miles south-east), Southcourt (10 miles south-east), Princes Risborough (13 miles south-east) and Haydon Hill (8 miles south-east).
Around Grendon Underwood
The countryside around Grendon Underwood includes Upper Ray Meadows.