Gus Potter Posted July 29 Share Posted July 29 (edited) Hello all. I know that a lot of folk talk about using D4 glue but this can lead to trouble. The designation D4 relates to the durability of the glue..durability is related to for simplicity the weather exposure.. you can buy D4 from say B & Q, Tool Station, Screwfix and loads of other places. Now I'm fine if you want to use "D4" that is bandied about on BH for sticking some non structural floor boards together. I'm not OK about you using this sole designation D4 (durability) in a stuctural application. A Tesco / Asda etc plastic bag is durable (probably deserves a D4 rating) for lying for years at the side of the road but it's not structurally strong! Glulam beams for example are bonded together with a structural glue that conforms to for example BS EN 301 which deals with glues that have structural stength AND the durability rating which is D1, 2, 3 & 4. Why would you not want to use a glue with both a structural and durability rating that the Glulam folk use? A structural glue requires both stength and durability. Structural glues tend to be resin based.. like old fashioned Araldite that your Mum and Dad used for fixing their glasses... Cascamite structural glue does the job and has both a structural and durability rating. Please folks can we stop recomending D4 when we are discussing bonding structural components. Edited July 29 by Gus Potter typo 5 1 Link to comment Share on other sites More sharing options...
Gus Potter Posted July 29 Author Share Posted July 29 To add a bit. I wrote this in response to a previous post by @Jawbkk who is thinking about fixing some floor joists that have had notches and holes drilled in them. One solution is to plate the joists up with ply. Simplistically the loads need to get into the ply.. round the notches and holes drilled for the electric cables and back into the solid timber. But if you use screws / nails etc then you need many and you can't get enough adequate spacing and edge distance for the nails etc. Also the more nails / scews you use the more risk you run in terms of damaging the already weakened timber. By using a structural glue you transfer the loads over a much wider area. You often just need a few screws to clamp the timber while the glue takes up. To check this type of timber joint if the right glue is used the SE now knows that the glue is stronger than the native timber. Then the SE checks not least what is called the rolling shear in the ply wood. This is the check to make sure that the diffferent layers of ply don't separate. The ply layers are bonded with a structural glue so why use a potentially inferior glue between the ply and the native timber? With a fair wind it then all falls into place and you have a sound solution. 3 Link to comment Share on other sites More sharing options...
SteamyTea Posted July 30 Share Posted July 30 Just to add to the above, gluing any materials together is more then just wiping the dust and oil off and squirting a bit of glue on the faces. Overclamping can cause problems as it squeezes too much adhesive out the gap, making gap shorter than the cured polymer length. Different polymers will have different directional mechanical properties, just like the materials they are joining. I like using adhesives, but would be very wary of sticking structural elements together on site. A year or so back, I stuck some ply to a plastic bench (down at the cafe in the woods). I must get down there and see if it is still in place. I also stuck some ply to a paving slab and left it propped up against the my house wall, shall try and dig that out and see what has happened. 1 Link to comment Share on other sites More sharing options...
Dave Jones Posted July 30 Share Posted July 30 only had to get a D4 caberboard up once, it came in bits and essentially had to be planed off the joist that's how strong the glue was. Pretty sure if you glued 4 x 100mm strips of OSB together you could easily hang a ton jumbo bag off them. Link to comment Share on other sites More sharing options...
SteamyTea Posted July 30 Share Posted July 30 37 minutes ago, Dave Jones said: Pretty sure if you glued 4 x 100mm strips of OSB together you could easily hang a ton jumbo bag off them. The question is for how long. It is why aging characteristics are important. 1 Link to comment Share on other sites More sharing options...
joe90 Posted July 30 Share Posted July 30 Very interesting, so does the structural glue used in glulams have a name? Link to comment Share on other sites More sharing options...
markc Posted July 30 Share Posted July 30 2 hours ago, joe90 said: Very interesting, so does the structural glue used in glulams have a name? A lot of timber laminating is done with Phenol resorcinol formaldehyde (hopefully the spelling/memory isn’t too far away). Been quite a few years since I’ve been involved with glulam structures Link to comment Share on other sites More sharing options...
Alan Ambrose Posted July 30 Share Posted July 30 A couple of years ago, as a teenager 😗, I used to help my dad build wooden boats. Cascamite and (if memory serves) urea formaldehyde were the glues for anything serious - which most stuff was. Link to comment Share on other sites More sharing options...
SteamyTea Posted July 30 Share Posted July 30 4 hours ago, Alan Ambrose said: Cascamite It is a urea formaldehyde resin, and probably the best wood adhesive there is. It does have a shelf life though, so don't use an old tin of it, even if it does seem to still be powdery. Some of the newer industrial polyurethanes are impressive, mainly because they can fully cure in minutes. These are often specially blended for a specific timber type, and more importantly, for the mixing pump machines. These days, adhesive tapes are often used, think if them as very high performance double sided tape. Curing is often initiated once a set pressure is reached. Link to comment Share on other sites More sharing options...
Gone West Posted July 30 Share Posted July 30 4 hours ago, Alan Ambrose said: I used to help my dad build wooden boats. Cascamite and (if memory serves) urea formaldehyde were the glues for anything serious In the fifties and sixties my Dad used animal glue for less serious work and Cascamite where some strength was needed. IIRC we used Cascamite when we built a Mirror dinghy at school in the sixties. Link to comment Share on other sites More sharing options...
joe90 Posted July 30 Share Posted July 30 So, we need a “named” structural glue that is available (apart from cascamite), any takers? Link to comment Share on other sites More sharing options...
SteamyTea Posted July 30 Share Posted July 30 43 minutes ago, joe90 said: So, we need a “named” structural glue that is available (apart from cascamite), any takers? Ureka is one, think I used called Aerolite. There are loads. Link to comment Share on other sites More sharing options...
OwenF Posted August 3 Share Posted August 3 (edited) Is it worth mentioning that ‘D4 glue’ also seems to be used synonymously with ‘PU D4 glue’ e.g. foaming flooring glue. as above, you can get D4 wood glue from Wickes, but the foaming stuff is not in many high street shops. I’ve found and have used Kronospan (purchased from Howarth Timber in Yorkshire), but at £16 a bottle!! I haven’t used much. (note: this product actually reports to be PVA but can confirm it does foam and fill gaps) did find an online place selling a brand I cant recall for about £5-6 a bottle, but I didn’t need to volume to justify shipping. Edited August 3 by OwenF Clarification on product type Link to comment Share on other sites More sharing options...
MikeSharp01 Posted August 3 Share Posted August 3 On 30/07/2024 at 19:00, joe90 said: So, we need a “named” structural glue that is available (apart from cascamite), any takers? We used Resorcinol PRF Resin Adhesive for our work, its a two part so needs carefully mixing. https://woodadhesives.akzonobel.com/en/adhesive-technologies/phenol-resorcinol-formaldehyde 1 Link to comment Share on other sites More sharing options...
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