Which Type of Greenhouse Glazing Seal To Use and How Much?

Which Type of Greenhouse Glazing Seal To Use and How Much?

Over the years many different types of glazing seal have been used by different Greenhouse brands, some brands have even used different glazing seal as they've developed new products, this guide will help you determine which seal to use when renovating your greenhouse and how much you may require

Glazing Seal Types

There are several types of glazing strip used to cushion the glass and provide a seal for greenhouses, some are interchangable and have different properties while some will only work on specific greenhouses, it's important to select the best type for your environment and for your particular glazing bar profiles.


Non Setting Butyl Mastic

Traditionally a non setting butyl mastic or putty was used as a gasket, this seal is still used in some greenhouses and provides an excellent seal by sticking to both the glazing bar and the glass or polycarbonate.

Butyl Mastic comes on a roll and is cut to size before being stuck onto the bars for the glass to be stuck into place, butyl mastic is quite sticky and can be tricky to work with but provides a very secure sticky cushion for the panels.

If you wish to keep your traditional greenhouse as original as possible of if you encounter extreme weather conditions then this may be the best type for you

We sell 150' and 200' rolls of this 4mm bead gasket





UV Stable Self Adhesive Foam Tape

Similar to butyl mastic in that it can be stuck over the top of old mastic after scraping the worst of it off the greenhouse bar; this flat tape seal can save a great deal of time and is very easy to use.

It can also be used on greenhouses where the glazing seal has to be threaded into or pushed into the glazing bars, with our self adhesive tape seal the old brittle seal can be either pulled out or cut down to the glazing bar with a blade to allow the new tape seal to simply be stuck on over the top.

This 25m roll of seal is 10mm wide to span over the glazing seal channel and 3mm deep to provide a good cushion for the glass, because it only sticks to the frame of the greenhouse and not the glass it is very easy to use and to do further work on the greenhouse if glass ever needs replacing or removing.




Crittall Equivalent Seal

Crittall Greenhouses were and remain a very popular garden building, they are no longer in production but they were excellently built and there are still hundreds if not thousands still being used and renovated in the UK, we have sourced an equivalent seal to their original 4mm glazing strip which simply pushes into the glazing seal channel in the bar

Our Crittall Seal comes in 15m Rolls




Elite Neoprene Glazing Seal

Elite Greenhouses have been in production for over 60 years and their most popular glazing seal has moved away from the traditional buytl mastic to a "thread in" neoprene seal, this seal is threaded into the glazing bars before the greenhouse is constructed and is very hard wearing and effective

Elite Seal comes in 15m or 50' Rolls




Halls Greenhouses Glazing Seal

Established in the 30s Halls Greenhouses have gone through many changes in their production processes and location, their seal has changed from a "push in" style in the past which is now best replaced with our self adhesive tape seal. 

Halls seal is now a "push on" style which is pressed onto a ridge on the glazing bar, this style is not interchangable with any other type of seal

Halls seal comes in 18m rolls which come as two runs stuck together, the 2 runs need peeling apart before use.




Eden and Juliana Seal

Eden and Juliana Greenhouses have also changed their seal design to a "push on" style however it has a slightly simpler profile to the Halls seal, their "U" shaped design simply pushes onto a ridge on the glazing bar and again is not interchangable with any other type of seal

We supply this type in both 31m and 63m rolls





Amount of Seal Needed for a Greenhouse

One of the most common questions we get regarding greenhouse glazing seal is "How much seal do I need for 6x8 / 6x10 / 8x8 / 8x10 / 8x12 etc. Greenhouse?"

We have a guide for the most popular greenhouses based on the average requirements for these sizes, greenhouse construction can vary quite significatly from brand to brand so it's best to measure exactly but our guide has proven very helpful in the past

6' x 8' Greenhouse - 190' / 58m

6' x 10' Greenhouse - 220' / 67m

6' x 12' Greenhouse - 250' / 77m

8' x 8' Greenhouse - 260' / 80m

8' x 10' Greenhouse - 300' / 92m

8' x 12' Greenhouse - 340' / 104m