Hampshire · England
Window & door mastic in Blackmoor, Hampshire
Mastic around window and door frames, sills and patio doors for householders, landlords and businesses in Blackmoor. ARBOMaster approved applicators, fully insured, with a one-year guarantee.
- Hard, cracked sealant around windows
- Black, perished sealant on frames
- Water coming in at the bottom corners of a door
Window mastic in Blackmoor
The mastic around a window or door seals the gap between the frame and the wall. Once that seal fails, wind and rain find the gap. The old mastic is removed and the joint resealed with a flexible exterior sealant. We work on aluminium frames, timber windows & doors and uPVC windows, and the jobs we see most are hard, cracked sealant around windows and cracked internal joints between frame and plaster.
Homes in small places like Blackmoor often stand in the open, with little to shelter their windows from wind and rain. That exposure dries out and cracks the mastic around frames and sills faster.
There’s a 12-month guarantee on every job.
- Place
- Blackmoor (GU33)
- Wider area
- Hampshire
- Guarantee
- 12 months on all our work
- Price
- A clear price before any work starts
- Telephone
- 0345 464 0079
- Page updated
- 26 October 2026
How to look after the new joints
No joint lasts for ever, but care makes a real difference. Our tips:
- Keep drainage slots and sill grooves clear
- Use gentle cleaners on frames and sealant
- Ventilate rooms so frames do not stay wet inside
- Don’t use solvent cleaners on the joint
Wipe the frames with soapy water when you clean the windows, and avoid solvent cleaners on the sealant.
Wet, windy weather is when failed mastic shows itself, but sealant goes on best when frames and walls are dry. Sorting cracked mastic early means the joint is sound before the bad weather.
How the visit works
There is not much for you to do on the day. Show us the job and we’ll take it from there. The job generally takes a few hours for a few frames, or a day or more for a whole house, including the tidy-up. In a small place like Blackmoor, access is usually the main thing to plan. If the job is outside, mention outbuildings, exposed walls and how to reach them.
- We start by checking each window and door with you.
- The old mastic is cut out and the surfaces cleaned back.
- Where gaps are deep, backing rod goes in first.
- A flexible, weatherproof sealant is applied in a colour to suit the frame.
- Finally we tidy up and check each joint.
Preparing for the visit
- Clear items away from the joints we are working on
- Let us know if you’ve seen damp or leaks
- Mention if the joints have been sealed before
Getting a quote
For a quote, ring 0345 464 0079 or drop us an email with the location and a short description of the problem. You’ll have a clear quote before any work starts.
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Also in Blackmoor
Windows and doors in Blackmoor
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 look after a building such as St Matthew's Church of England Aided Primary School, the mastic around its windows and doors needs looking after like any other building’s. Rented homes near Liss station change hands often, and cracked frame mastic tends to show up as a draught or damp complaint, so it’s worth checking between lets.
Blackmoor is about 5 miles south-east of Alton, in Hampshire. Across the GU33 area, our applicators can take on window mastic. Our area takes in 683 places across Hampshire, from the larger towns to small villages. Portsmouth is on our list too, around 21 miles away.
Our applicators cover all of GU33 for window mastic and the streets around it. Whether your property is on Blackmoor Road and Sotherington Lane or anywhere close by, our applicators can take on the job. We also cover Woolmer (1 mile south-east), Greatham (1 mile south), Longmoor (2 miles south-east), Passfield (2 miles east) and Weavers Down (3 miles south-east). Further out, we also cover Basingstoke (15 miles north-west), Farnborough (15 miles north), Fleet (13 miles north), Horndean (14 miles south-west), Aldershot (12 miles north-east) and Alton (5 miles north-west).
Near you in Blackmoor
Locally, jobs take us to homes and businesses close to Mill Chase Academy. The nearest railway station is Liss station, roughly 3.5 miles south. A little further out are The Romany Museum (2.3 miles west) and Chase Community Hospital (1.4 miles north-east). Open spaces near Blackmoor include Selborne Hill and Deadwater Valley.
Landlords, agents and businesses in Blackmoor
A neglected joint can let water reach the structure, which is a bigger problem in a rented property. Keeping joints in good order is simple maintenance that we can handle for you.
From a single let to a portfolio, you get the same standard of work: old sealant fully removed, joints prepared properly and a 12-month guarantee.
Blackmoor questions
Is Blackmoor in your area for window mastic?
Yes, Blackmoor is within the area we cover. We work across London and the South East. Just ring 0345 464 0079 or drop us an email with a few details of the job.
Do you work for landlords with property near Liss station?
Yes. We work for landlords and agents as well as householders. Just call 0345 464 0079 or email us with the address and what needs doing, and we’ll give you a clear quote.
Is the new sealant paintable?
Most silicone cannot be painted. If you plan to paint, tell us first and we can use a paintable sealant where it suits the joint.
What does window mastic cost?
It depends on the job, so we quote each one individually. For a quick quote, ring 0345 464 0079 or drop us an email with a short description of the job.
Do you remove the old sealant?
Yes. We cut out all the old sealant and clean the joint before applying anything new.
What sealant do you use?
The product depends on the job: sanitary silicone where it gets wet, and sealants suited to movement or weather elsewhere. Brands we use include Arbo and Everbuild.
Is it worth trying it myself?
For a simple, easy-to-reach joint, a careful DIYer can do a reasonable job. The usual mistakes are sealing over old sealant, sealing a damp joint and using too much.
Can you get sealant to suit coloured frames?
Yes. We can use white, brown, anthracite grey, black or clear.
When it isn’t the sealant
We’d rather tell you now than do work that will not last, so these are the limits:
- A failed sealed unit that has misted up
- Draughts through the window seals rather than the frame
- A sash or casement that won’t close properly
Not sure which it is? You can phone 0345 464 0079 or drop us an email and we will tell you honestly.
What we seal
- Timber windows & doors
- Patio & French doors
- Window sills
- uPVC windows
- Aluminium frames
- Composite doors
Different surfaces, different methods
Patio & French doors
Heavy door frames can move more than windows. The sealant must cope with it, where a rigid one would crack.
Timber windows & doors
Timber moves with moisture as well as heat, so the joint must stay flexible. We seal onto sound, dry paintwork or timber.
When to call us in Blackmoor
Some failures date back to when the windows were fitted. Mastic laid onto dusty, damp or crumbling surfaces never bonded as it should, so it comes away long before its time.
The most common problems we see are:
- Hard, cracked sealant around windows
- Mastic that’s falling out in pieces
- Cracked sealant at the sill ends
- Untidy mastic left by window fitters
If you live in an older home near St Matthew's Church, replacement windows fitted into old openings often leave uneven gaps that need backing and a flexible joint.
What your quote should include
- Is the old sealant removed completely?
- Whether the sealant suits the joint
- When the joint can take water or movement
- Is VAT in the price?
DIY sealant or a professional job?
The biggest DIY mistake is sealing over old sealant. Silicone does not stick to old silicone, so it peels away and traps moisture behind it. All the old material has to come out first.
Overfilling a joint is a classic DIY mistake. A thick, smeared bead looks untidy and does not move well, and getting the depth right matters as much as the look.