Glazing packers for window fitting
Updated: 23 October 2026
The new frame rocks when you let go, or the sash drops on the handle side after the glass is in. Glazing packers for window fitting are there to hold the outer frame at the fixings and to carry the sealed unit without covering the drains. They are not a FENSA certificate and not a test to BS 8213-4. This page stays on the window. The eleven listings are the [glazing blocks comparison](/hub/diy-supplies/glazing-blocks). Peter F. checked those listings. No claim here says any ASIN is certified. A qualifying purchase can earn a commission at no extra cost to you.
The new frame rocks when you let go, or the sash drops on the handle side after the glass is in.
The new frame rocks when you let go, or the sash drops on the handle side after the glass is in. Glazing packers for window fitting are there to hold the outer frame at the fixings and to carry the sealed unit without covering the drains. They are not a FENSA certificate and not a test to BS 8213-4. This page stays on the window. The eleven listings are the glazing blocks comparison. Peter F. checked those listings. No claim here says any ASIN is certified. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Footprint | Thickness | Pieces | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  EVOGES EVOGES 42-piece glazing packers | 28 × 100 mm | 1–6 mm, 7 of each | 42 | 8.4 | about £6.99 | View offer |
 FUX FUX 100-piece glazing packers | 100 × 24 mm | 1–6 mm | 100 | 8.8 | about £11.99 | View offer | |
| Best value |  Eleechen Eleechen 72-piece glazing packers | 100 × 28 mm | Mixed 1–6 mm; field says 6 mm | 72 | 7.4 | about £5.99 | View offer |
On this page
Pack the frame before you think about the glass
Installation packers sit between the outer frame and the opening, next to each fixing. The Glass and Glazing Federation’s section 3.12 says they should keep the frame central, level, and square, allow movement, and resist compression, rot, and corrosion. Over-tightening bows the jamb.
Sidey’s December 2024 guide uses corner fixings 150–250 mm from the external corner and centres no greater than 600 mm, with at least 40 mm of penetration into masonry for windows. Eurocell’s Logik steps use a 5 mm expansion gap. Foam is not the only fixing. Those numbers are not stamped on the amazon packs. On a door, add packers at hinges and locks. If you can only make the frame look square by bending it, stop.
Support the unit
Setting blocks carry the unit. Location blocks stop it walking. Glazpart puts them near the quarter points, generally not less than 30 mm from the corner, and wide enough for both panes. VEKA’s example is 30 mm under a 28 mm unit. The FUX 100-piece set is 24 mm wide, so it can come up short. EVOGES, Eleechen, the HuangXinyu 72-piece set, and Vurixfo are the 28 mm listings. Yonfas claims 28 × 100 mm and also prints 1 × 2 × 3 cm.
Toe and heel is a diagonal, not a pile of packers in every corner. Conservatory Land’s note, for a side-hung window, puts bottom packers on the hinge side and top packers on the handle side. If that disagrees with your diagram, follow the diagram. A cracked or misted unit is a failed seal. Packers will not clear the mist.
Leave the water a way out
VEKA’s Norscot guide keeps glazing blocks off the drain slots and uses bridge packers on the lower rail, minimum two, and more if the rail is longer than 1,500 mm. A flat plate across the slot does not leave that path. None of the eleven listings is a bridge packer. The FUX ventilation-channel line is a groove, and B0H5BYTQJ8 is a horseshoe for a screw, not a bridge.
What a bag of packers does not certify
Replacement windows and doors in existing dwellings in England and Wales are Building Regulations work. FENSA is a government-authorised scheme for that work, and a certificate from a registered installer shows compliance. GOV.UK says that without a competent-person scheme you submit a building notice or full plans. The homeowner remains responsible, including for DIY. Northern Ireland and Scotland have their own routes.
A bag of packers is not a FENSA certificate, not a Building Regulations application, and not safety glass under Approved Document K. BS 8213-4:2016 and BS 6262 are cited as identifiers only. No amazon ASIN here is described as tested to either. If the building is listed or you cannot support both panes and keep the drains open, call a competent installer or Building Control.
Common questions
Where do setting blocks go on a fixed window?
Near the quarter points of the bottom edge, generally not less than 30 mm from the corner, unless the window manufacturer places them at fixings between the corner zone and the quarter point. That is Glazpart’s appendix, not a measurement taken on these packs. Location blocks then keep the unit plumb at the sides and top. Do not shove every block hard into the corner, and do not cover a drain slot while you do it.
What is toe and heel on a side-hung sash?
It is packing on a diagonal so the glass holds the sash square and the handle side does not drop. Conservatory Land’s note uses bottom packers on the hinge side and top packers on the handle side. Your profile manual wins if it draws a different diagonal. Packing all four corners equally is the version that lets the sash drop. Bridge packers on the bottom, where the system asks for them, keep that support from blocking the drain.
Will a flat packer stop the window draining?
It will if it lies across the drain slot. VEKA’s guide keeps blocks off the slots and uses bridge packers on the lower rail, at least two, and more on a rail longer than 1,500 mm. A flat from this set can still be a setting block if it sits clear of the slot and is wide enough for both panes. It is not a bridge packer because the listing says ventilation channel.
Do packers make the installation compliant with Building Regulations?
No. In England and Wales, replacing windows or doors in an existing dwelling is Building Regulations work, shown by a competent-person scheme such as FENSA or by Building Control. FENSA’s published scope leaves out glass-only repair, listed buildings, outbuildings, conservatories, commercial property, and buildings over 18 metres. Packers are a fitting detail. They are not the certificate.
What if I only replace the glass?
FENSA says glass-only repair sits outside its scheme. You still have to support both panes, keep the drains open, and use setting blocks where the system puts them. A misted unit needs a new unit, not thicker packers. If the frame is rotten or out of square, glass-only is the wrong job and the opening needs a proper survey. The pack size for one sash is a small 1–6 mm mix, not a 20 mm shim set.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 21 October 2026.
- GGF installation guide, section 3.12 (retrieved 21 October 2026)
- BSI BS 8213-4:2016 summary (retrieved 21 October 2026)
- FENSA homeowners (retrieved 21 October 2026)
- GOV.UK building work, replacements and repairs (retrieved 21 October 2026)
- Glazpart glazing accessories (retrieved 21 October 2026)
- VEKA Norscot installation guide (retrieved 21 October 2026)
- Sidey survey and installation guide, December 2024 (retrieved 21 October 2026)
- Glazing Supplies Direct: how to use glazing packers (retrieved 21 October 2026)