Plastic shims vs wooden shims
Updated: 23 October 2026
A bathroom plinth that has swollen, a patio door that sticks after rain, or a dry internal door that only needs a millimetre at the hinge are three different gaps. Plastic shims vs wooden shims comes down to moisture, shape, and whether glass is involved. Use plastic where damp would swell timber, a timber shim where you can see it and replace it, and a flat packer for glass. The [Plastic wedges](/hub/diy-supplies/plastic-wedges) comparison ranks twelve plastic packs. This page does not re-price them. The files were read on 21 October 2026. We did not certify any wedge. A qualifying purchase can earn a commission at no extra cost to you.
A bathroom plinth that has swollen, a patio door that sticks after rain, or a dry internal door that only needs a millimetre at the hinge are three different gaps.
A bathroom plinth that has swollen, a patio door that sticks after rain, or a dry internal door that only needs a millimetre at the hinge are three different gaps. Plastic shims vs wooden shims comes down to moisture, shape, and whether glass is involved. Use plastic where damp would swell timber, a timber shim where you can see it and replace it, and a flat packer for glass. The Plastic wedges comparison ranks twelve plastic packs. This page does not re-price them. The files were read on 21 October 2026. We did not certify any wedge. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Shape | Material line | Limit | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  HongNuoEn HongNuoEn 50 mixed plastic wedges | Two short tapers, 6 mm and 8 mm | Plastic | Measure on arrival; six reviews | 7.5 | about £6.99 | View offer |
| Alternative |  n/a Lokatall 8 red glazing wedges | Long wedge, about 175 mm | Plastic | Thickness lines disagree | 5.8 | about £9.99 | View offer |
 n/a 10 black furniture wedges, stated 6 mm | Short taper, stated 6 mm | Plastic | Reviews are furniture, not glass | 7.8 | about £4.59 | View offer |
On this page
Where timber loses
In a bathroom, under a patio threshold, or beside an external frame, a pine wedge can swell and soften. EWI Store and Packers Direct argue that polypropylene does not rot the way timber does. Those are shop pages. They do not cite a British Standard. If the gap stays wet, plastic is the material that will not feed the damp.
MacBlair, a Northern Ireland fixings merchant, separates the words: a shim is often the wedge, and a packer is often the flat piece of a stated thickness. Check the millimetres on the plastic wedges buying guide. A waterproof wedge can still be the wrong object.
Where a timber shim can still be the piece
Timber still has a place where it stays dry and you can see it. A thin wooden shim under an internal hinge can be trimmed and replaced when it crushes. A plastic furniture wedge will also do that dry job, but it is not the only honest choice indoors.
Do not carry that habit into a bathroom or a frame that takes driving rain. Nothing in these twelve files is a timber shim, so this page does not rank a pine price. A fence slot is a separate case, on the fence panel wedges page.
A plastic wedge is not a flat packer
Calling a wedge plastic does not make it a glazing packer. The wedge changes height as you drive it. The packer is a flat piece of stated thickness. Screwfix sells Easyfix packers, 100 × 28 mm, stepped from 1 mm to 6 mm, at £14.99 for 225 including VAT. That price is not a row in this set.
Lokatall is the long glazing-style wedge here. Its thickness lines disagree, and an untested 30 ton sentence is not a measured load or a BS 8213-4 certificate. Onspeshow's composite and waterproof lines have no reviews and no blend specification. Under glass, you want the flat packer the system allows.
What the window codes ask you to remember
The Glass and Glazing Federation guide, section 3.12, asks for packers that resist compression, rot, and corrosion. They are normally left in place, and fixings should not be over-tightened. That does not appoint any Amazon wedge as the packer. BS 8213-4:2016 covers the survey and installation of windows and external doorsets. As stated on the BSI page, it does not cover fire doorsets or roof windows. No pack here claims a fire test.
Glazpart, referring to BS 6262 practice, puts support blocks at least 30 mm from the corner. Fix Direct uses about 100 mm, with the packer slightly wider than the glass and the drains clear. Do not average those figures. Follow the system supplier's drawing. Damp gap: plastic that will not rot. Dry visible interior: timber you can replace. Glass: flat packers, drains clear. An 11 metre limit was not found as a Building Regulations rule, so it is not a ban you can apply from here.
Common questions
When is a plastic wedge better than a timber shim?
Use plastic where the gap stays damp: a bathroom, a patio threshold, or an external frame. Timber swells and can rot there, so the thickness you set does not stay put. Merchants sell polypropylene on that basis. They are shop arguments, not a British Standard citation, but the moisture point is sound. Plastic is the material. It is not automatically the right shape, and a furniture wedge is still the wrong part under glass.
Is every plastic wedge a glazing packer?
No. In trade speech a shim is often the wedge and a packer is often a flat piece of stated thickness. Screwfix's Easyfix packers are the flat object, 100 × 28 mm, stepped from 1 mm to 6 mm. Lokatall is the long wedge in this set, with disagreeing thicknesses and an untested load line. Onspeshow's composite and waterproof lines are seller wording, with no reviews and no blend specification. None of these Amazon wedges is shown as certified to BS 8213-4.
What does BS 8213-4 actually require you to remember?
BS 8213-4:2016 is the code of practice for surveying and installing windows and external doorsets. The point to remember from the Glass and Glazing Federation's section 3.12 is practical: packers should resist compression, rot, and corrosion, they are normally left in place, and fixings should not be over-tightened. The BSI scope, as stated, does not cover fire doorsets or roof windows. The standard does not name any pack in this Amazon set, and this page does not quote the standard text.
Why do two UK trade notes give different distances from the corner?
Glazpart's note puts support blocks at least 30 mm from the corner, drawing on BS 6262 practice. Fix Direct describes a working distance of about 100 mm, with the packer slightly wider than the glass and the drains kept clear. Those figures are not a range to average into 65 mm. They are two trade notes. Use the distance on the system supplier's drawing for the frame you are installing, and leave the drainage path open.
What about a fire door?
Fire doorsets sit outside the scope of BS 8213-4 as stated on the BSI page, and roof windows do too. No pack in this set claims a fire test. A plastic furniture wedge or a timber offcut under a fire door is not a tested seal or a tested packer. If the door is a fire door, stop and follow the fire-door manufacturer's instructions, or ask a competent fitter, rather than packing the gap from a general shim bag.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Listings captured 21 October 2026. Updated 23 October 2026.
- GGF installation guide, section 3.12 (retrieved 21 October 2026)
- BS 8213-4:2016 windows and doorsets (retrieved 21 October 2026)
- BS 6262:1982 glazing code (retrieved 21 October 2026)
- General Product Safety Regulations 2005 (retrieved 21 October 2026)
- Consumer Rights Act 2015, section 11 (retrieved 21 October 2026)
- Fix Direct: how glazing packers are used (retrieved 21 October 2026)
- Homebuilding: stop fence panels rattling (retrieved 21 October 2026)
- Beko UK: how to level a washing machine (retrieved 21 October 2026)