Wooden Window manufacturing, beads inside or outside? Which is best

[deema]

Ok, I’m guilty of watching far too many uTube videos whilst quarantined, but it’s got me wondering. When I make windows and doors with lights I place the beads externally, why, because that how I was taught to do it. Others make them with the beads on the inside. So, using traditional tennons, properly scribed, is there an advantage to weatherproof or longevity for putting the beading on the inside?

I appreciate that security and ease of changing the units would suggest internal beading is the way to go.

Ive also seen Bradshaw Joinery, a uTube Chanel he cuts a drip groove in the rail directly under where the glazing unit will sit (ie glazed unit sits on top of the drip groove) which is machined through the top of the tenon to the outside to let out any water that does get in. I’d never thought of doing it, I can see advantages to doing it and also for a panelled external door where the bottom of the panels always rot iyt over time. Again, does anyone do it, any thoughts?

 

[johnnyb]

my thoughts are it has an inbuilt failure. they usually have a fake putty angle scribed on the outside and the bead is mitred around the inside. this seems to make manufacture more straightforward as its always the angle that's scribed. and the bead is simply mitred. the rebate being drained
I'm not entirely sure how this technique came about tbh. upvc were mitred externally until security issues were highlighted. you think it's solely to make changing units easier?

 

[johnnyb]

draining the cavity seems pretty forlorn as even with an angle I don't reckon it would drain tbh. I reckon a lot of that manufacture relies on accoya and quality paint sprayed on thickly. I was on holiday examining a nice timber conservatory. it had a 12 degree slope underneath the casements but it had no capillary grooves it was always wet everytime I opened it . it was 5 years old and had barely deteriorated. despite being constantly wet.

 

[johnnyb]

I think double glazed units breaking down is preventable but the glass industry is skewed towards upvc being easy to replace a failed unit. it's a much bigger pain with timber no matter how it's made.

 

[deema]

I’ve come across Q-Wood clip on beading which allows window rebate cavities to be vented and drained. Nit fitted u5 myself or have any experience, so started a thread to see if anyone else has. I find it very interesting that their pinned beading they don’t seal to the frame, only use glazing tape and pins, no silicone between bead and frame.

 

[Spectric]

I find with UPVC systems they don't seem to bother with water ingress into the frames, they just accept this and provide drainage at the other end. The issue arises when an installer overlooks drilling a drainage hole and then it fills and you get water into your property. I find that one of the better ones are the Rehau profiles, some of the others are really not good. Also with UPVC these days it is all internally beaded for no other reason than security, far to easy to remove a sealed unit that is externally beaded, so was it the criminal fraternity that originally came up with that idea to make their life easier.

 

[deema]

Cheers Roy, I was actually thinking specifically about wooden windows, by bad, I’ve now changed the title. Appreciate your post.

 

[Doug71]

I still bead mine from the outside, it just seems like if the beads are on the inside any water that gets in is directed inwards.

Also there is a good chance the external bit at the bottom just in front of the glass will be one of the first bits to rot, much easier to replace if it's a bead rather than a solid piece of frame.

This is what I tell myself anyway, probably I'm just old and stuck in my ways.

 

[deema]

Good point Doug, thinking about it, if the window starts leaking it means the seal has failed and it’s a good indicator that remedial work is required before rot sets in. I kind of think that’s a positive to internal beading?
I agree though, the lower rail beading always seems to rot.

 

[Ollie78]

I think beads outside are more prone to rotting over time, there is effectively one horizontal and one vertical gap for water to sit in once it gets in.
I have repaired countless windows like this, where the outer glazing bars come off in line with the face of the glass because water has sat behind the bead.

I don't use beads at all just make them traditionally and bed and face with hybrid polymer.

Ollie

 

[Jones]

Definitely external beading. I use aluminum bottom bead from Exitex because a wooden bottom bead will rot very quickly. Glazing tape to the frame allows a bit of movement, angled setting blocks under the unit keep it above any standing water and allows draining. Tape on the beading is neater and easier than mastic and stainless screws hold better than nails. If you want a proper job copy the big window manufacturers who offer long guarantee's or check out Trada website.

 

[Richard_C]

I have conventional wooden casement windows, house built 1987. The beads are external which strikes me as a bit bonkers for security: my insurance requires locking window handles but if you tried you could get in with the aid of a paint scraper and screwdriver to lever the beads off - no need to break anything.

The house was 9 years old when we moved in and some of the DG units were already misted up inside. I got a glass fitter to do the fixed panes upstairs because I'm not great with ladders: he said they had been installed badly so they sat in the bottom of the rebate and the beads hadn't been sealed. He put 2 or 3 small plastic spacers under each pane (pane needs to be slighty undersize) and sealed the bead-to-glass meeting point with a clear silicone.

25 years later the ones he fitted and the ones I fitted to the ground floor and the removable upstairs casements (most original ones failed soon after the first batch) are all still fine. As per the post above, the key seems to be making sure the bottom edge of the glass unit doesn't sit in water.

 

[Jones]

For security you can't remove the unit if it's been fitted with double sided glazing tape without running a knife blade all around the inside of the unit. You cannot remove the unit from the outside.

 

[niall Y]

I’ve come across Q-Wood clip on beading which allows window rebate cavities to be vented and drained. Nit fitted u5 myself or have any experience, so started a thread to see if anyone else has. I find it very interesting that their pinned beading they don’t seal to the frame, only use glazing tape and pins, no silicone between bead and frame.

Hi There
I used to place the beads on inside of all my D/G wooden windows and doors, but a few bad experiences of having them leak, with the resultant call-backs, made me switch to placing the beads on the outside. For the most part an interior bead will be fine especially in sheltered locations, however, exposed locations require a belt and braces approach. For this I used to use a clip system from Reddiseals, which sounds similar to your Q clips. The bottom bead I made wider than the side beads, and was more of a mini-sill, with a capillary groove to the underside front edge.
Both approaches have their merits,but exterior beads are better at keeping the water out. Cheers, Niall

 

[deema]

Hi Niall,
thanks for posting, that looks an interesting system. Do you still use it? What are the main reasons you chose it? Im guessing the clips are to facilitate dry glazing? I’ve always used wet glazing sealant, however, Im intrigued by dry glazing systems, I’ve had a look the Reddiseals system, did you use it or something else? Did you provide a drain for the rebate? I’m assuming all dry systems need to have a vented rebate? However, watching their dry glazing video it suggested that the beading was pinned and there didn’t appear to be a vent to the rebate? I would have thought water would have undressed at the mitres of the rebate requiring a vented rebate. Sorry for all the questions.

 

[niall Y]

Hi Deema,
Quite a few questions there. I'm retired so very little joinery done now. The Reddiseals system was the one I used for D/G windows , and there are a few spacers and clips still knocking around the workshop. It is a dry system with a stick on rubber tape to supply the seal,The plastic spacers keep the D/G unit clear of the top, sides and bottom of the rebate, metal clips to fix is securely in position, ( they can only be easily removed wit a special tool).
I used to pin the beads in place with dome headed stainless pins. I tried various methods with the bottom bead to stop it sitting in the bottom rebate the most successful of which was to raise it up on small pads to allow water to drain away.
You can put a slight downwards slope on the bottom rebate, to assist drainage, but you will then have to allow for this when you cut in any vertical glazing bars.
Often it's easier to leave things square, and accept that there is no truly perfect solution. Hope this answers some of your questions. Niall

 

[eribaMotters]

I've tried to count up and I reckon between 1983 and 2013 I made and double glazed about 250/280 openings in doors and windows. The vast majority where in joinery grade softwood. Rebates inside and a struck 45 chamfered edge on the outside to resemble a puttied effect. All surfaces and interior beading had a spirit based preservative applied and then aluminium primed. Units sat on blocks and glazed with double sided glazing tape. A thin smear of butyl applied on the top edge over this and the internal beads given a smear of butyl to sit against the aluminium foil tape that was wrapped around the unit edges.
I am aware of 4 units failing, so the method would appear to be fairly good and I'll continue with this approach when next needed.

Colin

 

[deema]

Hi Deema,
Quite a few questions there. I'm retired so very little joinery done now. The Reddiseals system was the one I used for D/G windows , and there are a few spacers and clips still knocking around the workshop. It is a dry system with a stick on rubber tape to supply the seal,The plastic spacers keep the D/G unit clear of the top, sides and bottom of the rebate, metal clips to fix is securely in position, ( they can only be easily removed wit a special tool).
I used to pin the beads in place with dome headed stainless pins. I tried various methods with the bottom bead to stop it sitting in the bottom rebate the most successful of which was to raise it up on small pads to allow water to drain away.
You can put a slight downwards slope on the bottom rebate, to assist drainage, but you will then have to allow for this when you cut in any vertical glazing bars.
Often it's easier to leave things square, and accept that there is no truly perfect solution. Hope this answers some of your questions. Niall

Thanks Niall, got to ask, can you feel and toe the units with packers or do the clips do this?

 

[deema]

I've tried to count up and I reckon between 1983 and 2013 I made and double glazed about 250/280 openings in doors and windows. The vast majority where in joinery grade softwood. Rebates inside and a struck 45 chamfered edge on the outside to resemble a puttied effect. All surfaces and interior beading had a spirit based preservative applied and then aluminium primed. Units sat on blocks and glazed with double sided glazing tape. A thin smear of butyl applied on the top edge over this and the internal beads given a smear of butyl to sit against the aluminium foil tape that was wrapped around the unit edges.
I am aware of 4 units failing, so the method would appear to be fairly good and I'll continue with this approach when next needed.

Colin

Thanks Colin, that’s really good to know. A couple of years ago I made a door for my house that’s North facing so gets all the weather with internal rebates as an experiment / test. It’s held up perfectly, but, long term testing would take too long, so really appreciate your long term experience.

 

[deema]

Thanks Colin, that’s really good to know. A couple of years ago I made a door with DGU lights for my house that’s North facing so gets all the weather with internal rebates as an experiment / test. It’s held up perfectly, but, long term testing would take too long, so really appreciate your long term experience.