The perimeter joint between a window or door frame and the surrounding structure is one of the most critical seals on any building. Get it wrong and you're looking at draughts, condensation, water ingress, and in worst cases, mould and structural damage. Get it right and the building performs as designed from day one.
Sycamore Sealants provides specialist window and door perimeter sealing for new build developments, commercial fit-outs, and refurbishment projects across South East England. We work with uPVC, aluminium, timber, and steel frame systems, and with all common substrate types including brick, render, concrete, and masonry.
Window & Door Sealing Services
- External Perimeter Sealing — Weatherseal between frame and external wall finish. Correctly tooled and finished to shed water away from the joint.
- Internal Perimeter Sealing — Airtight sealant application between frame and internal reveals. Reduces draughts and prevents condensation within the reveal.
- New Build Programmes — Volume window and door sealing for housing developments and apartment blocks. We work efficiently across plots to meet programme.
- Commercial Glazing — Curtain wall perimeter joints, shopfront sealing, and commercial entrance systems. Internal and external applications.
- Replacement Window Sealing — Sealing around newly installed replacement windows in existing properties. Removal of old failed sealant and full re-application.
- Rooflights & Skylights — Perimeter sealing for roof-mounted glazing elements where correct application is essential to prevent water ingress.
Product Selection for Windows & Doors
External window and door sealing requires a product that is UV-stable, paintable where required, and compatible with the frame material. We specify neutral-cure silicone for uPVC and coated aluminium frames (acetoxy-cure silicones can attack certain coatings), and appropriate polyurethane or acrylic products where painting over is required.
For internal perimeter sealing, we use flexible acrylic sealant where painting is required, and silicone where the joint will remain exposed. Colour is matched to the surrounding wall finish or frame colour.
New Build Window Programmes
We're experienced working alongside window installation teams on new build developments to provide immediate perimeter sealing as frames are installed. This prevents water ingress to the structural opening during construction and ensures the building envelope is closed as quickly as possible.
For larger programmes, we can discuss phased attendance to stay with your build programme across multiple plots or floors.
Frequently Asked Questions
Do you seal both inside and outside?
Yes. A properly sealed window or door has both an external weatherseal and an internal airtight seal. These serve different purposes and should both be present. Many installations have only one or neither — we can assess and advise when quoting.
Can you work with uPVC, aluminium, and timber frames?
Yes. We're experienced with all common frame materials and select the appropriate sealant product for each. This is particularly important for coated aluminium and coloured uPVC frames where the wrong product can cause staining or adhesion failure.
How long does window perimeter sealant last?
External window sealant typically lasts 10–15 years if correctly specified and applied. UV exposure, thermal movement, and frame quality all affect service life. We can advise on expected performance when quoting.
We have failed sealant on existing windows — can you replace it?
Yes. We remove all old sealant, clean and prepare the substrate, and apply fresh product. We don't apply new sealant over old — it won't last and masks the underlying issue.