New timber sash windows - big gaps on the inside?

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Hello all, I'm having some new softwood timber windows installed as I write. They are replacing some top-hung pvc windows (that I think replaced the original sash windows long before I moved in). If relevant, they are spiral balance rather than cords & weights.

Confused/slightly concerned about something. They are being installed brick-to-brick (there's a "reveal" which I guess is standard for sash in victorian properties?). From the outside, the gaps on the edges look pretty small. They filled (temporarily I assume for weather-proofing last night) with expanding foam.

On the INSIDE, however, there are huge gaps. Expanding foam again yesterday, and he's removing it at the moment.

One of the fitters (very nice bloke but a bit of a language barrier) said something about my frame being 45mm rather than 100mm which explains the gaps. Is this normal? I'm wondering whether it is and that large gap would be where the sash box would originally have sat? He said the gaps were the same before with pvc windows, and they were filled and then finished with wood trim.

Any comments or explanations would be much appreciated!


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Sash always had wood trims inside to allow for the weights .sp the opening will be more inside and as you say would expect it to be neatly boxed to look original.
 
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Sash always had wood trims inside to allow for the weights .sp the opening will be more inside and as you say would expect it to be neatly boxed to look original.

Thanks Cross Thread, that's helpful and puts my mind at rest a bit!

I also hope those gaps don't affect soundproofing - I went for thicker 6.4mm laminated glass in one of the panes, a bit pointless if the frame isn't well sealed!
 
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The boxes were removed when it was converted to pvc by the look of it and the reveals lined with timber. From the outside the windows were measured brick to brick and look acceptable, looking at the frame size it's too thin for them to be made wider/taller and be set behind the brickwork as the frame would get lost, trouble is that size has to transfer to the inside and depending where the reveals are set which looks like they are set wider than the brick width so hence the gaps, so long as the gaps are fully foamed and the gaps are nicely trimmed out then all should be ok
 
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One of the fitters (very nice bloke but a bit of a language barrier) said something about my frame being 45mm rather than 100mm which explains the gaps

he is 100% correct.

The new softwood sliding box sashes are I presume spiral balances with a solid frame. (45mm thick)

the originals would’ve been traditional sliding sashes with weights. Those would’ve had a box frame comprising of pulley stiles and in and out facings to form a box. The facing were typically about 100mm wide.

Looking at the images, I would say they are making a nice job of the install and the windows are measured correctly - box sashes should be measured between the brickwork outside and overall frame sized so there is about 20mm to 35mm of outer facing visible when viewed outside. Internally liners and trims are fitted as needed to make up any gaps.
 
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the inset windows were required in London after 1666, and other fashionable towns or nearby districts copied the style. Doorframes, too.

windows-great-fire-london_clip_image019.gif


When I moved away I was surprised to see windowboards in other regions.


people with an eye for historic homes like yours would be nauseated by anything else.
 
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Thank you Crank / Notch / John!

Sounds like everything is proceeding as it should then. It's slightly odd as when they originally came to measure up, they removed some of the external pvc trim and pointed out the reveal, saying that the new sash windows would fit in here (and therefore wider than the brick-to-brick that is visible from the outside).

This is why I was confused about the gaps. But I'm now assuming they said this because they didn't know I would be going for spiral balance (and therefore 45mm rather than 100mm frame) at that point.

Pic below of how it looks at the moment from the inside. You can't see it very well, but as well as the main trim, he asked me whether I wanted a quadrant trim all the way round. I didn't have a strong opinion, asked him what he would do, and he said yes, thinks it looks nicer like that. We'll see!

Current progress.jpg
 
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I have a friend with a small historic home in Australia.

The sliding sashes are competently made but have no balance, you lift them, and a wooden cog holds them in position.

I suppose that would have been easy for a good joiner with a plane, saws and chisels, but no local industrial infrastructure to make or import the other parts.
 
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Hello again everyone, just an update. They are finished on the inside, photo attached. Looks neatly finished to my untrained eye.

Confused about the exterior though. They haven't finished, but as you can see they've chosen to finish the sides with mortar. I'd asked them at the start whether they would be using a wood trim, and they said they'd be doing this which is better.

From the attached 2 things - firstly they've done the bottom and the sides but not the top. That's just lazy, surely?

Secondly, the colour massively stands out against the brick and looks very unattractive to me. In my neighbourhood I can't see any other building with sash windows that is finished like that. I've attached another photo of an aluminium window I had done at the back of the property a few years ago, and they seem to have used a red coloured mortar finish, which to my eye fits in much better/stands out a lot less.

Obviously my mistake at not establishing these details when getting the quote, but to be fair I'm not an expert and didn't really enter my mind to ask. I guess, from my standpoint, what should I reasonably be expecting them to do? One of the fitters said I could subsequently paint the mortar, but surely that should be their job?!

Any guidance appreciated, as ever.
 

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No expert, but I would expect the mortar to soon crack and eventually fall out, due to differential expansion between bricks and wood.
 
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No expert, but I would expect the mortar to soon crack and eventually fall out, due to differential expansion between bricks and wood.

I think that's trowelling mastic - correct stuff for the application.
 
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Thank you Harry and mrrusty - I asked them while they were doing it, and they said it was sand & cement, so just regular mortar. I've just read that trowelling mastic has as plasticizer in it to help with movement/flexibility, so guess that would have been much better.

I also understand I'm meant to leave the mortar to cure for at least 28 days before painting.
 
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Thank you Harry and mrrusty - I asked them while they were doing it, and they said it was sand & cement, so just regular mortar.

Cheapest fix for the gap, but as said - it will eventually crack and fall out. I would insist they use the proper materials to fill the gap.
 
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