Shropshire Building Skills - Specifying Adhesives, Fillers and Sealants

Specifying Adhesives, Fillers and Sealants (posted 12th May 08)
All types of building and DIY jobs these days depend upon the use of various adhesives, fillers and sealants. Once where screws, nails or more sophisticated jointing was the order of the day, now all manner of substances can be used to great effect, helping to save time and simplify many tasks.

Adhesives are now regularly used for bonding materials such as UPVC, glass as well as the more the obvious areas involving wood and metal. Glue types like PVA are in regular use not only for bonding materials together but also for priming surfaces (in diluted form). Waterproof variants are also often specified. Contact adhesives are regularly specified for large sections of metal, plastics, or decorative features such as coving for instance. Often available in tube type cartridges (requiring a dispensing gun), grab adhesives are used again for large sections or areas where nails or screws are to be avoided or are less desirable. If used properly according to the manufacturers instructions, grab adhesives can create very strong bonds. Resin style adhesives are made up of two elements, which are mixed at the point of use. Possibly somewhat superseded by the availability of ready to use cartridge glues, resin does still find a place especially where strong bonds are required such as anchor points for shelving - when used in conjunction with screws or expanding bolts etc.

Take a glance in any large DIY store and the choice of sealants can be bewildering. Many sealants have some kind of waterproofing (or resistance at least) and are often formed from a silicone mixture. Generally available on cartridge form not only are there sealants for differing jobs but there are often colour choices as well. It's well worth reading exactly what a sealant is best used for before you end up with the wrong substance for the job. Bathroom type sealants are often very resistant to water and often mould. They're obviously great for sealing around sinks, showers, baths and so forth, but are not next to resistant when it comes to accepting a painted finish. Often referred to as 'high modulus', bathroom sealants offer less flexibility as opposed to 'low modulus' sealants, which are often recommended for glazing work. A great universal option is decorators caulk which can be used in a massive array of jobs. Caulk can be a bit of a lifesaver for filling in around window frames, skirting boards, doors, as well as general cracks in walls and ceilings etc. It's possibly best to avoid overuse though; although it'll help you patch in a few errors here and there it should be thought of as remedy for poor work. Overuse can be a bit glaring obvious especially if time hasn't been taken to clean, smooth and perhaps paint.

One final, but nevertheless, invaluable filler material is expanding foam. Used in areas where gaps are so large regular fillers can't be used, expanding foam offers a quick and effective solution. Being polyurethane-based, it's worth checking heat tolerance if filling in around heating flues and the like.

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Steve Hinks – www.shropshirebuildingskills.co.uk
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