Shetland Islands · Scotland
Gunnista Window Mastic
Professional window mastic in and around Gunnista, with old sealant always removed completely and a 12-month guarantee.
- Gaps between the frame and the inside reveal
- Leaking joints at the ends of sills
- Damp patches on the reveal after heavy rain
How we handle window mastic in Gunnista
The new joint does not have to be white. We can seal in white, brown, anthracite grey, black or clear, so the line suits the frame instead of standing out. We work on patio & French doors, window sills and aluminium frames, and the jobs we see most are gaps left after new windows were fitted and damp patches on the reveal after heavy rain.
In and around a place like Gunnista, homes range from older stone-built cottages to newer houses. Exposed frames and sills take the full force of wind-driven rain, so the mastic there works hard.
We stand behind the work with a 12-month guarantee.
- Where
- Gunnista (ZE2)
- Wider area
- Shetland Islands
- Guarantee
- A year, on every job
- Quote
- A clear price before we start
- info@mrmastic.co.uk
- Page updated
- 26 October 2026
How it works
Our applicators work methodically: protect, prepare, seal, tidy. For most jobs that takes a morning for a couple of windows and a door and we leave things clean and tidy. Somewhere like Gunnista may be a longer drive, and the journey is planned ahead. Mention tracks, gates, ferries or anything else about the route.
- 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.
- We apply a weatherproof sealant to match the frame and tool it neatly.
- Finally we tidy up and check each joint.
How to prepare
- Where the joints are inside, avoid wetting them before we arrive
- Mention any parking rules near the property
- Clear the area around the work
Get a quote
If you’re in Gunnista and need window mastic, send an email to info@mrmastic.co.uk. A short description of the job and where it is helps us quote, and we will agree the price before any work begins.
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More services for Gunnista
Should I try it myself first?
If you’ve already had a go yourself, that is fine. We remove it and do the joint properly, so tell us about it when you ask for a quote.
Too much sealant is as bad as too little. A heavy bead looks messy and copes badly with movement, and getting the depth right matters as much as the look.
What the job involves on each surface
Timber windows & doors
Soft or rotten wood cannot be sealed successfully. We’ll point out any rot we find, as that’s a job for a joiner.
Aluminium frames
Aluminium needs a sealant that bonds to coated metal, and acetoxy silicones are not used, as they can attack some metals. We use a neutral-cure product.
Why act early in Gunnista
The work is quick compared with the damage it prevents: it takes a morning for a couple of windows and a door. Leave it until water is coming in and you may need plastering and decorating as well. Out of town in Scotland, exposed walls take a lot of weather, and damp in stone or harled walls takes a long time to dry once water gets behind a joint.
Leaving a failed joint generally makes the job bigger, not smaller. If you’re not sure whether it needs doing, send an email to info@mrmastic.co.uk and we will give you an honest view and a quote.
Why book with us
- An ARBOMaster approved applicator
- We are fully insured
- Colour agreed with you before work begins
- Anti-fungal sanitary silicone in wet areas
Read our cost guide or what customers say.
Aftercare tips
A little care helps the new joints last. We recommend:
- Keep solvents and bleach off the sealant
- Walk round the house once a year and look at the joints
- Do not paint over the silicone
- Don’t aim a pressure washer at the joints
A yearly look round the frames is enough. Small splits are simple to catch before they leak.
On timber windows, water behind the joint can lead to rot. Once wood has rotted, it needs repair before it can be sealed, so it pays to reseal before that happens.
FAQs for Gunnista
Do you cover smaller places like Gunnista?
Yes. Gunnista is within the area we cover, which takes in towns, villages and rural addresses. Our work covers the whole of Scotland, including the islands, where work is planned around ferry crossings. Let us know about access, parking and anything unusual about getting there when you book.
Is window mastic in a coastal place like Gunnista any different?
Coastal homes put outside sealant through more weather than inland ones, so preparation and the right sealant matter all the more. Walls facing the sea are usually the first to need attention.
Can tenants book the work?
Yes, but check with your landlord or agent first. Landlords are often happy for the work to be arranged.
Can you work on commercial sites?
Yes, regularly. We can plan bigger jobs in stages to suit the site.
How long does it take to reseal the windows on a house?
The work takes a few hours for a few frames, or a day or more for a whole house. Access and the amount of old mastic make the biggest difference.
Where is Mr Mastic based?
Mr Mastic is based in Crawley. We cover Gunnista and the rest of the Shetland Islands, along with the rest of our area.
Can I paint over the new sealant?
It depends on the sealant. Some hybrid sealants can be painted; silicone can’t. Tell us if you’re decorating and we will choose accordingly.
Do you guarantee window mastic?
Yes. Every job comes with our one-year guarantee, and we are ARBOMaster approved applicators.
What we are called out for in Gunnista
Frames are never completely still. Sun on a frame makes it expand, and it contracts again overnight, while the masonry beside it stays put. If the sealant can’t stretch, it splits.
It’s worth asking for a quote if you see:
- Cracked sealant at the sill ends
- Rain getting in at the frame or under the sill
- Hard, cracked sealant around windows
- Rushed sealant from a window installation
In the older streets around St Ola's Church and burial-ground, the joint between an old wall and a newer frame is normally the first place rain gets in.
Before booking anyone
- How long to leave it before use
- Whether they seal over old material or remove it
- How much experience the applicator has
- What preparation is included
What window mastic looks like in Gunnista
Gunnista is within about 1 mile of the coast, and homes near the sea take more wind-driven rain, with salt in the air closer to the shore. That is hard on the mastic around window and door frames, especially on the side facing the sea. Sash and case windows are common in older Scottish homes, often pointed into the wall with traditional sand mastic.
Schools such as Anderson High School are buildings too, and the mastic around its windows and doors needs looking after like any other building’s.
Gunnista is in the Shetland Islands. From the centre of Gunnista to the outskirts, window mastic is available for homes and businesses alike, from flats and houses to offices and hotels. Gunnista is one of 63 places in the Shetland Islands where we work.
Jobs for window mastic in ZE2 is quoted and booked the same way as anywhere else. If you are just outside Gunnista, we cover Heogan (1 mile west), Gremista (2 miles west), Grindiscol (2 miles south), Lerwick (2 miles south-west) and Sound (3 miles south-west). Remote and island addresses need a little more planning, so please mention your location when you email us at info@mrmastic.co.uk.
Near you in Gunnista
Nearby you’ll also find Shetland Museum (2 miles south-west) and Montfield Hospital (2.2 miles south-west). The countryside around Gunnista includes Loch of Aith.
When something else is needed
It helps to know what we can’t do too:
- Damp problems in the wall away from the window
- Misting between the panes of a double-glazed unit (that needs a new unit)
- Soft or decayed wood in the frame
If in doubt, drop us a line at info@mrmastic.co.uk and we will say what we think.
Where we work in Gunnista
- Composite doors
- uPVC windows
- Window sills
- Patio & French doors
- Aluminium frames
- Timber windows & doors