Fitting aluminium framed windows

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Davidkinton

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I've just ordered some new sliding aluminium Windows for my Buckingham cruiser and I am now looking for advice on fitting them. The cabin sides are 3mm fibreglass. What sort of sealant would be best? Butyl tape, non setting mastic, silicone sealant? What fixings should I use? Inter screws, pop rivets, screws and nuts or wooden battens behind and screw through? How would they be finished inside the cabin? I'm thinking of using Veltrim as a covering. Sorry for all the questions but I want to do it right.
 
Davidkinton said:
I've just ordered some new sliding aluminium Windows for my Buckingham cruiser and I am now looking for advice on fitting them. The cabin sides are 3mm fibreglass. What sort of sealant would be best? Butyl tape, non setting mastic, silicone sealant? What fixings should I use? Inter screws, pop rivets, screws and nuts or wooden battens behind and screw through? How would they be finished inside the cabin? I'm thinking of using Veltrim as a covering. Sorry for all the questions but I want to do it right.
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Butyl tape is very popular. easy to use and not messy to use like a sealant

Arbomast BR is a non setting butyl sealant favoured by some.

Many modern sealants such as the polyurethanes like Sikaflex and PU40 and the hybrid polymers like CT1 or StixAll are also powerful adhesives which may make later maintenance difficult.

Silicones are the ones most frowned upon.

Interscrews probably give the neatest finish with simple countersunk or raised heads. It would be normal I think to fit an inner bezel. This would conceal the edge of the lining.
 
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I've just fitted new windows to mine, and used butyl tape. If your windows have radiused corners, it's a bit fiddly at the corners, but not too difficult. My windows have external flanges, and I put the tape on the flange then put the window in place. My GRP is at least 10mm, so mine are fixed with self tappers, and the internal lining hides any intrusion. With your 3mm I would use Interscrews or similar, maybe with an internal trim.
 
There is no one, best way rto fix windows - you must think it through based on the advice you receive and other installations you have seen and chose your own way. I've been involved inreplacing windows which were simply sheets of acrylic screwed down onto mastic and we used interscrews. Very neart outside but the inside without any internal frame looked like an iron maiden! From your description, my first reaction is to suggest that you use butyl tape, for ease of application and flexibility and make up a fairly chunky wooden inner frame and screw into that with self tappers (woodscrews). That way you don't have a line of fasteners showing inside and the screws will hold the frame as strongly as the rather thin GRP can withstand. It also makes it much easier to butt up against with any hull lining. Should you decide to use mastic from a tube, I'd advise you to put thin washers on each screw between the frame and the cabin side. That way, when you screw down you can't squeeze out all the mastic by overtightening.

Rob.
 
I have quite a lot of experience with windows, although mine are just plain bolt through to interscrews. On original purchase the aft cabin windows were leaking badly and I bought Scapa tape through Hadlow Marine, and this was a very successful (and still holding) fix. Shortly after, Gladys was t-boned on her mooring and the port top sides and deck were split, with the crack nicking off the rear corner of the saloon window - so required replacement. The collider's insurance paid and she went to Fox's, who put two new windows in (couldn't match the shade of the existing one) with sikaflex.

Well, they were waterproof for about a year, and I finally gave up about three years ago. I got Hadlow to come out and fit new again with the bedding tape and it's been brilliant. There is some "maintenance" on big windows in that you may have to tighten the screws down carefully over the first year, but that's it. Obviously they're also easily removable (mind you the sikaflex'd ones "fell off" when the screws were removed) to enable tape replacement if necessary. Hadlow changed the recommendation between my aft cabin and main cabin from applying the tape to the window, to applying to the opening, and on one aft window one small piece of tape started to "creep" and form a loop, but that was a 20 minute job
 
Gladys said:
There is some "maintenance" on big windows in that you may have to tighten the screws down carefully over the first year, but that's it. Obviously they're also easily removable (mind you the sikaflex'd ones "fell off" when the screws were removed) to enable tape replacement if necessary. Hadlow changed the recommendation between my aft cabin and main cabin from applying the tape to the window, to applying to the opening, and on one aft window one small piece of tape started to "creep" and form a loop, but that was a 20 minute job
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That has been quite a problem on my little motorsailer. The windows are big sheets of perspex that seem to have been removed several times in the past with the result that some of the screws don't fit the GRP very well. I used butyl tape for bedding but did not tighten the screws enough. After a few months the tape looked like a frilly pelmet, almost every length drooping between the screws. One window is bedded on Arbomast, which has not suffered the same problem but extrudes almost constantly (and looks bad through clear perspex)
 
vyv_cox said:
That has been quite a problem on my little motorsailer. The windows are big sheets of perspex that seem to have been removed several times in the past with the result that some of the screws don't fit the GRP very well. I used butyl tape for bedding but did not tighten the screws enough. After a few months the tape looked like a frilly pelmet, almost every length drooping between the screws. One window is bedded on Arbomast, which has not suffered the same problem but extrudes almost constantly (and looks bad through clear perspex)
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Worth noting, although not relevant to the OP, that Arbomast BR is not UV resistant.

From the Tech data sheet:

UV Resistance: Not suited to applications exposed to
direct sunlight​
 
I bedded my windows using butyl tape from a caravan shop. ITS INCREDIBLY STICKY. The way to cope with the corners is to just bend the tape round in a series of straights, making sure there's sufficient that, when tightened up, some extrudes from under the frame.
Seems to work fine and stay flexible. As I see it, you don't need UV resistance as its all protected by the ally frame.
Or will I regret it one day?
 
The black bedding material which had been originally used to seal the glass of my windows into the aluminium frames, 23 years ago, had become cracked and brittle, presumably due to sunshine. Don't know what make it was, but it was letting some water seep in. I took the opportunity to splash out, and fit double-glazed replacements.
 
Presume your aperture filling went well? For the windows I would fit timber frames inside and screw into them you can then fit further timber strips inside the superstructure to attach the interior trim panels.
 
Davidkinton said:
Anyone had any success using neoprene with aluminium frames rather than butyl?
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Yes, we fitted neoprene on our previous boat with Aluminium frames. I seem to recollect using gloop as well. I think it was Mastic type stuff as we were advised that Sikaflex would be too permanent. The new windows (which were screwed into internal wooden frames in the saloon) worked. i.e. The leaks stopped.
 
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