Sealing joints for: Movement and connection joints, Facade elements, Balconies, Window and door frames, Pre-cast elements, Infill panels. (TDS p.1)
- Temperature stated in TDS
- −40 °C to +70 °C (TDS p.2)
- Pack
- 300 ml cartridges
Step-by-step solution
Window and door frame sealing
Sealing the gap between aluminium, uPVC, steel or timber frames and the wall, plus glass-to-frame and interior finishing joints. This is a common place for monsoon rain to get into a home.
- 6 steps
- 5 products
- 4 answers
You need this when…
- Rain getting in around window frames during storms
- Damp patches below window corners
- Old sealant around the frame cracked or shrunk
- Gaps and cracks around door frames on the inside
The work, step by step
General guidance based on the manufacturer data sheets. Site conditions differ: confirm the system with MCT before you start. Where we do not name a product, ask us and we will confirm the right one.
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Step 1: Check the gap and clean out
Remove old sealant. The substrate must be sound, clean and dry (Sikaflex AT Connection p.3). Sikaflex AT Connection takes joints 10–35 mm wide at a 2:1 width-to-depth ratio (Sikaflex AT Connection p.2). For wider gaps, ask us.
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Step 2: Backer rod and pre-treatment
Insert a closed-cell polyethylene backer rod (Sikaflex AT Connection p.3). For high-performance joints, clean and pre-treat aluminium, PVC and powder-coated frames with Sika Aktivator-205, and prime porous masonry with Sika Primer-3 N (Sikaflex AT Connection p.4).
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Step 3: Outside frame-to-wall joint
Sikaflex AT Connection is listed for window and door frames, facade elements and balconies. It is primerless on most substrates, with ±25 % movement (Sikaflex AT Connection p.1). Sikaflex Construction AP covers movement and connection joints on porous substrates, indoors and outdoors (Sikaflex Construction AP p.1).
Sikaflex AT Connection Sika Request a quotation Other options for this stepAsk us The right product here depends on your site. We confirm it before naming it.
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Step 4: Glass-to-frame and shopfronts
Sikasil WS-305 S is a weather seal for windows and curtain walling, for experienced professionals only (Sikasil WS-305 S p.1). Sikasil-712 WS suits shopfronts and glass partition walls where a translucent or metallic look matters (Sikasil-712 WS p.1). Do not use either on polycarbonate or acrylic sheet (Sikasil WS-305 S p.2; Sikasil-712 WS p.3).
Sikasil WS-305 S Sika Professionals only Request a quotation Sikasil® WS-305 S can be used for weatherproofing sealing applications where durability under severe conditions is required. (TDS p.1)
- Pack
- INFORMATION Unipack 600 ml
Sikasil-712 WS Sika Sikasil®-712 WS is designed for weather proofing and sealing applications where the sealants appearance is of importance (translucent/metallic look). (TDS p.1)
- Temperature stated in TDS
- +5°C to +40°C (TDS p.2)
- Pack
- 300 ml cartridge, 12 cartridges per box
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Step 5: Inside joints before painting
Sikacryl-110 fills interior joints around windows and doors, is mildew resistant, takes ±7.5 % movement, and can be over-painted (Sikacryl-110 p.1). Sikacryl S also covers connections around window and door frames, and crack filling inside and out (Sikacryl S p.1).
Sikacryl-110 Sika Sikacryl®-110 is designed for interior crack and joint filling with low movement. Sikacryl®-110 is also suitable for duct sealing in HVAC applications. Main applications: Head of wall joints, Wall joints, Interior joints around windows and doors, Around the penetrations, As a gap filling in the c… (TDS p.1)
- Temperature stated in TDS
- −20 °C min. / +70 °C max (TDS p.2)
Sikacryl S Sika Request a quotation Sealing joints for: Interior joints on many types of substrate with a limited amount of movement, Connections around window and door frames, Around wall and ceiling penetrations Crack filling:, Internal and external cracks not exposed to permanent water immersion. (TDS p.1)
- Temperature stated in TDS
- +5 °C min. / +35 °C max (TDS p.2)
- Pack
- 300 ml cartridge: 12 cartridges per box.
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Step 6: Tool and finish
Tool the sealant firmly against the joint sides. Mask the edges for neat lines and remove the tape within the skin time (Sikaflex AT Connection p.4). Paint over Sikaflex AT Connection only after a compatibility trial (Sikaflex AT Connection p.3).
Proposal brief
Window and door frame sealing: scope and system
A starting point for a site proposal. Quantities, prices and the final specification follow a site visit or photos.
Scope of work
- Removal of old sealant around x windows and doors
- Backer rod, pre-treatment and external frame sealing
- Interior joint filling ready for paint
- Glass-to-frame resealing, where needed
System build-up
| Step | Product | Pack | Source |
|---|---|---|---|
| 3. Outside frame-to-wall joint | Sikaflex AT Connection | 300 ml cartridges | TDS p.1 · May 2021, Version 03.01 |
| 4. Glass-to-frame and shopfronts | Sikasil WS-305 S (professionals) | INFORMATION Unipack 600 ml | TDS p.1 |
| 4. Glass-to-frame and shopfronts | Sikasil-712 WS | 300 ml cartridge, 12 cartridges per box | TDS p.1 · May 2025, Version 02.01 |
| 5. Inside joints before painting | Sikacryl-110 | — | TDS p.1 · May 2025, Version 04.01 |
| 5. Inside joints before painting | Sikacryl S | 300 ml cartridge: 12 cartridges per box. | TDS p.1 · May 2021, Version 01.01 |
What we need from you
- Number and sizes of windows and doors
- Frame material (aluminium, uPVC, steel, timber)
- Wall finish around the frames (plaster, stone, cladding)
- Photos of leaking corners, inside and outside
- Access for upper floors
Site conditions
- Dry joints and dry weather during sealing (Sikaflex AT Connection p.3)
- Joint widths within 10–35 mm (Sikaflex AT Connection p.2)
Not included
- Frame repair, re-fixing or glass replacement
- Leaks through wall cracks or the roof, which are quoted separately
- Access equipment for high windows, unless agreed
Questions customers ask
Can I paint over the frame sealant?
Sikaflex AT Connection can be over-painted after a compatibility trial (Sikaflex AT Connection p.3). Sikacryl-110 can be over-painted (Sikacryl-110 p.1). Silicones such as Sikasil-712 WS cannot (Sikasil-712 WS p.3).
Will it stick to uPVC and aluminium frames?
Sikaflex AT Connection is primerless on most substrates (Sikaflex AT Connection p.1). For high-performance joints, PVC and aluminium are pre-treated with Sika Aktivator-205 (Sikaflex AT Connection p.4).
Can I use the same sealant on the glass?
No. Sikaflex AT Connection is not a glass sealant (Sikaflex AT Connection p.3). For glass-to-frame, a silicone weather seal such as Sikasil WS-305 S is listed (Sikasil WS-305 S p.1).
Is acrylic filler enough outside?
Sikacryl-110 is for interior joints only (Sikacryl-110 p.1). Outside, use an elastic sealant listed for window frames, such as Sikaflex AT Connection (Sikaflex AT Connection p.1).
Steps and product facts are taken from the manufacturer data sheets (page cited). Products are named only where the data sheet confirms the use; quantities follow a site visit or photos. General guidance: check the data sheet or ask us before you start.