Exterior wood glue

[Adrian]

HI Folks

If it ever stops raining - I'll be adding a small extension on to the timber Studio - somewhere to park the ride-on mower and other bits & pieces.

Construction will be 4" x 2" framework with metail profile sheets 'bolted' on (are they screws or bolts..? - little hex-head self-tapping things with a washer).

I wanted to make the framework as sturdy as possible - so was even considering some rudimentary half-lap joints and even some bolts.

Some parts of the structure (like doors) will be prone to sagging - so I was considering using some sort of adhesive to strengthen the joints.. - as well as judicious cross-bracing

What's the current thinking for adhesive that's not going to be exposed to the full force of the Irish summer - but might get damp from time to time ..? One of the 'Sticks-like-whatever' mastic products, outdoor PVA or a.n.other ?

Thanks Adrian

[The Medway Handyman]

When attaching newell posts to 6 x 2 decking joists, I half lap the post and use Pinkgrip D4 (toolstation sell it) and four 6mm x 90mm Turbogold coach screws. Given a few hours it would be easier to pull a sailor off your sister than shift one.

Turbogold coach screws are excellent for this sort of job, straight in with a drill driver, no pilot, no splitting, great 'pull tight' ability and very strong.

[marpate1]

Epoxy resin? The wood will split before the joint breaks down.

[Adrian]

Aha - never heard of Pinkgrip D4 - I'll ask around....

I'd never heard that expression - how quaint !

Yes - have to look around for some of those (or similar) If it's what I'm thinking of you'd end up with the 'head' protruding...?

- really want to end up with a flush finish so maybe I'm stuck with _serious_ screws. Used bolts on the carport (connecting 6" x 2" onto 4" square uprights) - but it's a fiddle (drill only just long enough, swapping between drill & driver bits, bolts 'just too short' so cutting a recess with a spade bit - while up a ladder - bleagh!)

I know I should get bolts the right length (but I've got a spare box-full of the 'slightly too short' ones - and it seems a shame to waste them )

Did treat myself to a 2-drill Ryobi one-plus kit just before Christmas so looking forward to trying it 'in anger'....

Thanks Adrian

[Adrian]

'Spose so - bit of a fiddle though with the 2-pack mixing etc...

Thanks Adrian

[Rod]

Agreed about 2-part.

I would consider both waterproof PVA and polyurethane (e.g. Elch from Screwfix). Polyurethane seems OK outside - subject to being hidden/protected from UV.

But, I would avoid glue in general, if possible. I have used a little to 'mend' a bit of fencing - and, so far, it has been great. But I would not wish to use it in a critical application.

[The Natural Philosopher]

Foaming polyurethane glue. Nothing else will be as good. Or as expensive.

I do not recall the brand names.

[The Natural Philosopher]

But sadly the brittleness of the glue ensures that this will happen early. You will get separation at the glue line.

Thats why the foamed poly glues are better..they retain a bit of flexibility, and they distribute the stress over a wider area.

However as someone else pointed out, screws or bolts are better than all the glues ever made.

[Steve Firth]

Screwfix polyurethane glue is relatively cheap.

[Rod]

Agreed. Not quite as cheap as PVA, but if final volume were the criterion (rather than bottle size), possibly cheaper? (Actually very similar per ml price to the Evo-Stik Exterior at Screwfix. But towards twice as much as Isaac Lord own brand waterproof PVA.)

From Screwfix:

Elch D4 Polyurethane Wood Glue 750g Light Brown.

Solvent-free, rapid-setting adhesive for use in larger applications. High resistance to seawater, weathering and chemicals. Excellent adhesion to many substrates such as wood, chipboard, metals and laminates. Complies with EN 204 Class D4.

Quote No: 79242 Pack Prices (inc. VAT) £8.80

That is what I bought and have used. It seems to be fine but I have no other for comparison.

[meow2222]

You can get it in twin carts with a self mixing nozzle. Piccy here:

be beguiled by PU, it works but it has some real shortcomings. The slight foaming action is in practice useless since foamed PU has next to no strength. Also although its totally proof as long as it dries out, it fails completely if it stays wet for many days. Its not totally waterproof as is so often claimed. Epoxy is better.

But imho more sensible would be to add 45 degree bits of wood at the right angle joints. These stiffen the structure as well as reinforce it, and if screwed these are far more durable than any glue joint.

NT

[Steve Firth]

You can get it cheaper than that in the "No nonsense" range in cartridges:

No Nonsense Polyurethane Wood Glue 310ml NO NONSENSE 200

310ml. Polyurethane based, rapid setting adhesive for use in smaller areas. Excellent adhesion to most substrates and high resistance to chemicals, sea water and weathering. EN 204 D4 From £6.45 Polyurethane Wood Glue 310ml Quote No: 34168

OK, less than half the quantity, but a cheaper pack.

I think the "Joiner's Mate" range is also polyurethane, but I haven't used that one.

Gorilla Glue and Bison Glue are common trade names.

Other cheap sources are:

I also think that when considering price, one needs to consider that it doesn't take much PU glue to make a good joint.

[robgraham]

I used PU glue recently for much the same task - the frame for the external doors for 3 sheds.. I just used half joints and reinforced the joint with screws. Weatherboard went on the outside.

I used PU from a bottle once and hated it - and it set on its own accord in the end. Cartridge is much easier - if you want a quick set, you dampen one of the surfaces. It does have the disadvantage that it is sticky and not water soluble so cleaning it off requires white spirit, etc.

Rob

[The Medway Handyman]

Apparently it originates from Chatham Dockyard.

[The Medway Handyman]

Thats exactly when you should use it. Not on its own to be sure, but to reinforce the mechanical join.

In the newell post to deck joist application you can feel the difference when the glue has set.

[The Medway Handyman]

I think the 'D4' bit is the standard to look for.

[Adrian]

I'd never have guessed !

Adrian

[Adrian]

In my case it's kind of belt & braces...

The extension is an add-on to the timber-built studio - with a pent roof which will follow the same line as the existing. All 4 x 2 with metal profile cladding.

Trouble is - even though I can get a good solid fixing to the shed wall

- the wall that's parallel to the shed isn't going to be so easy to secure - and is going to rely on a mixture of gravity, good luck and 'rawlbolt' fixings into a couple of pre-existing concrete kerbstones (probably). No opportunity for digging holes & sinking in metposts - we're practically on bedrock...

Not such a big issue at the back of the shed - where I can run a 4 x 2 across at ground level to stop the upright going walkabout - but most of the front of the shed is taken up with a pair of doors - so there will be a tendency for the front upright to want to splay out....

As the ride-on mower will be stored in the shed - can't really have a 4 x 2 across the base / front.... unless it's treated well and sunk in the ground....

Messy old job - wanted ways of bracing the upright to save it from moving - triangular timber braces may well be the best way yet....

Why is life never simple ?

Adrian

[The Natural Philosopher]

All the easy bits like breathing and sex, have already been done.

[Dave]

So why could I not breath and have sex this morning? :-)

Though I did have a toy in my lap the day before and no cough :-) But no wife in the bed.

Dave