# Box Sash Windows



## John Smith (14 Sep 2008)

My first post... so hello to everybody

My woodworking is a hobby and involves mainly furniture making.
I am in the process of refurbishing the house that my wife and I move to 18 months ago and the time has come to replace the windows.

I plan to build double glazed sliding box sash windows and am looking for some advise.

First, what timber should I use for the windows. Is it normal to build the box and sash out of different timbers (to keep the sash as light as possible)?

I intend to paint the windows but would prefer to use a hard wood that is resistant to rot.

Second, can anyone recommend a book or a source of plans which detail typical box sash window construction.

Thanks


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## MikeG. (14 Sep 2008)

John,

I don't know if you are familiar with Mumford & Wood, who are a top quality UK manufacturer of timber windows and doors, both "conservation" and "contemporary"? 

They make the most wonderful sliding sashes, which look absolutely first-class and yet come with double glazing, plastic staff and parting beads and draught seals everywhere.

As an architect, I have specified these in a number of projects and have yet to see a better reproduction sash.

They have full product drawings available on their website http://www.mumfordwood.com and some reasonably useful sections in their catalogue. I think their web-site drawings are only available in Autocad format, but if you ring them and ask for a PDF version (don't tell them that this is so you can copy their stuff!) they may be willing/able to help.

If they can't and you ask me really nicely on a day when I am not rushed off my feet, I could possibly import the Autocad drawings and convert them to PDFs for you. Bearing in mind the Copyright issues involved, this would have to be for your own personal use and interest.


I hope this helps

Mike


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## John Smith (14 Sep 2008)

Thanks Mike, excellent web site with lots of useful information


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## ET (25 Sep 2008)

Hi,
I replaced my box sash windows and door/frame using The Window Works who use Russian Pine they are not cheap but the quality of workmanship is superb- all custom built to fit your dimensions and not pre-designed. They also encased my art nouveau glass as part of the box frames so I could keep the original design. The door and frame had to be built out of hardwood all to the original design. I have part of a 1908 victoria house so all the doors windows, are none standard size. Anyhow, have a look at page 215 in the revised edition of the Reader's Digest complete DIY manual it will give you a break down drawing of all the components but no dimensions used.

This old house - has some interesting comments http://www.thisoldhouse.com/toh/article ... 81,00.html
Good luck.


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## AndyT (25 Sep 2008)

John - I don't want to sound negative - and I applaud your intention of keeping timber window frames - but do have a look at the building regs side of things first. I think you'll find that for a new window, there are rules about dimensions to which mean a much chunkier look than you might want. Also, the window trade have done their best to establish a 'closed shop' where only registered installers are allowed.

There's some good general info on the scams of the UPVC merchants at http://www.askjeff.co.uk/ and some threads elsewhere on this site showing modern trade methods. 

Andy


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## MikeG. (25 Sep 2008)

No, there is absolutely nothing to stop you making and installing your own windows unless you live in a listed building. Your double glazing supplier will produce compliant units for you........and there is nothing whatsoever to say you have to use chunkier sections than are traditional. 

AndyT.......could you do a little digging and try and find out where this rumour has come from?

Mike


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## joiner_sim (25 Sep 2008)

I make these things every few weeks, so I know how they work, any questions just get in touch with me.

To install windows these days, you need a FENSA certificate, and the windows also needs to be approved by building regs. If you are installing the windows yourself, without a FENSA certificate, you can get an officer of some sort to come out and check them and them you will get the certification required..... pretty sure thats how it works, anyway......


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## apj101 (26 Sep 2008)

im never one to "break the law", but really you have to admit that building regs in this case are total rubbish. Im fine with building regs on new builds, but in this case he is taking out an old sash and basically replacing them....why the heck does that new building regs....i know it does, but its shouldn't 
i mean if he left the old frames there to rot away the build inspector would be fine with that, but as soon at you put new ones in suddenly all these rules and regs become important....if they are so important why were the old rotting ones "fine"
grrr makes my blood boil
Im not saying break the law, you do what you feel is right but if it were me I'd just replace them and not say anything, if anyone asks id jsut say they were like that when i moved in.
personally Ive knocked out walls, and re-wired my entire house without "inspection" why? coz i know what im doing. If i were using some dodgy builder i may get the inspector in, but since i know im doing it right i dont bother..."it was like that when i moved in sir"

ohh look at that rant


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## ET (26 Sep 2008)

Whilst I also get disgruntled about newer building regs, it is worthwile reading them - the specs for newer windows include specific details about anti-shatter windows and approved kite marks which are for specific heights so that if they should shatter for whatever reason individuals get the least damage caused to them. This I approve of.

One sheet of my 60's secondary glazing before I replaced all the sashes fell out hit my shoulder and flipped over me as I was cleaning the windows. The glass splintered and sharded everywhere - it was not a shatter resist glass and I was extremely fortunate that I stayed still and waited until everything had landed - 6ft x 3ft pane - not a cut on me but I was picking up glass shards for weeks and the carpets plants and various other things got shredded - good job nobody else was in the room.


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## agbagb (26 Sep 2008)

Hi John,
It sounds like you are at the same stage as I was a year ago. I've researching drawing up plans and have made a small test window. I've got the timber (swedish and russian redwood) ready to make the first full size one. I'll be painting, with good design rot should not be a problem.
I've made a few posts on another forum (Hi Mike nice to come across you here as well and thanks for your input). Not sure if its polite to post links to those threads?

I'll intend writing a blog covering the details as I'm making them. Many people seem to be interested and are asking similar questions. 

Trada have just published a summary of regs http://www.trada.co.uk/downloads/constr ... 008_V1.pdf. you might have to log in first.

You should get building regs approval if its a DIY job. If it was free I'd be getting it. But the windows I'm planning will be up to spec, safety, energy etc. But I'm loathed to pay to be told that and I'll be moving out of this house in a box.

I'll post a link to my blog when I've started it. 

Andy


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## MikeG. (26 Sep 2008)

Hi Andy,

no, I think the correct form is to keep the two forum (fori ??!) seperate. You can, of course, copy and paste relevent text easily between the two.

Mike


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## agbagb (26 Sep 2008)

I've just read the rules and it looks like I can post to other forums so you might be interested in having a looking at these.
www.getwoodworking.com/forum/forummessa ... /1/V/1/SP/
and
www.getwoodworking.com/forum/forummessa ... &V=5#16397

andy


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## agbagb (26 Sep 2008)

Hi Mike,
Posts crossing in the ether. Sorry if I've got that wrong. It looks like the moderator will make a judgement. I'll live and learn.
Andy


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## MikeG. (26 Sep 2008)

Andy,

mine wasn't a reading of the rules.......it was an interpretation of what I have seen others do once or twice. We're probably both right, and I don't think you will see a moderator over this!!

Mike


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## Jake (26 Sep 2008)

Mike Garnham":1ut5mfr0 said:


> Hi Andy,
> You can, of course, copy and paste relevent text easily between the two.
> 
> Mike



Strictly speaking, only if it's your own words rather than someone else's.


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## RogerS (26 Sep 2008)

apj101":vu2t51nr said:


> im never one to "break the law", but really you have to admit that building regs in this case are total rubbish. Im fine with building regs on new builds, but in this case he is taking out an old sash and basically replacing them....why the heck does that new building regs....i know it does, but its shouldn't
> i mean if he left the old frames there to rot away the build inspector would be fine with that, but as soon at you put new ones in suddenly all these rules and regs become important....if they are so important why were the old rotting ones "fine"
> grrr makes my blood boil
> Im not saying break the law, you do what you feel is right but if it were me I'd just replace them and not say anything, if anyone asks id jsut say they were like that when i moved in.
> ...


Hear hear...couldn't put it better myself. If you're not intending to sell in the not too distant future then go down the DIY route. Try and keep the dgu's 4-6-4 and that way you will end up with nice neat glazing bars as opposed to the 4x2 that most modern windows seem to be made of.

EDIT: Also if you search the forum for sash you'll find a lot more info...including some excellent how-to's IIRC by jfc.


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## John Smith (3 Oct 2008)

I have just logged in for the first time in a while as I work away from home and have seen all the replies to my question, thank you all for your suggestions and idea's. I will be taking a closer look at each one.

The house I have bought originally had sash windows but at some stage most were replaced by that horrible aluminium secondary glazing that was popular back in the 70s or 80s. The house is not listed but is in a conservation area and the local authority is keen for the windows to be replaced with timber frame types and that is a condition on the planing permission they have granted. 

What I want to avoid is having to commission somebody else to make and fit them when I am capable of doing that myself, so I will have to clarify exactly what the building regs state.


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## RogerS (3 Oct 2008)

John

If the originals were only signle glazed then I think you should be able to reason with BC that whatever you're putting in will be better insulation-wise then what was there before. So you should be able to use 4-6-4 K glass possibly argon filled which will get your u-value pretty close as makes no odds. 

You may get hassle from them regarding making them 'fireman friendly' but if you want to you can politely tell them to swivel as that reg only applies to new builds. 

The only other possible niggle is if trickle vents are a particular 'pet' topic of whichever BC officer you get. There still seems to be some discussion as to whether this rule has been relaxed or not. And IMO pointless for sash windows.

Roger


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## Steve Maskery (3 Oct 2008)

When I made mine earlier this year, I queried the ghastly trickle vent requirement. The BCO was happy for me to use a traditional air brick instead. I don't even think he checked.

Also he didn't bat an eyelid when I said I wanted to make my own frames. I just told him they would be to current regs and he was happy about that
over the phone.

S


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## agbagb (3 Oct 2008)

If you're going down the regs route, then I think you might have to go for 4-16-4 K glass. You can get away with less if you have argon filled. 
I'm not having glazing bars so I don't need to worry about the thickness showing there. 
I've started contructing mine now and will, when I've got time, post progress reports on a Blog.


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## Jake (3 Oct 2008)

agbagb":bd07u1w2 said:


> If you're going down the regs route, then I think you might have to go for 4-16-4 K glass. You can get away with less if you have argon filled.



4-6-4 will do for renovations (not new build) if you use Argon filled Optitherm units, with a following wind and a sensible BCO.


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## Shadowfax (3 Oct 2008)

'fireman friendly' 
Huh?

SF


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## RogerS (3 Oct 2008)

Shadowfax":119corja said:


> 'fireman friendly'
> Huh?
> 
> SF



Sorry..bit obtuse..I was referring to the windows being able to open sufficiently so that firemen can get inside easily.


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## Jake (3 Oct 2008)

I always thought it was people being able to get out of them that was the concern - maybe over the shoulder of said fireman in desperation.


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## RogerS (3 Oct 2008)

John..forgot to add that there are a couple of 'How To make sash window' threads over at t'other place.

And while we're talking about the BC/Fensa niceties of windows, let's not forget the insistence on those wee little nylon brushes that are slid into a routed groove...already to suck up water and rot your windows in a couple of years time. :evil: Decently made windows don't need all that faffing about IMO.


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## Shadowfax (3 Oct 2008)

I'm there now!! Nothing to do with firemen getting in, Roger. We are talking about escape windows for getting out of the building at lower levels when the internal layout does not lend itself to using the doors.
Believe me if firefighters want to get in there is not much that will stop them.
I used to really enjoy kicking in doors!
Don't get the chance these days, though!
Shame. How sad. Never mind!

SF


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## agbagb (6 Oct 2008)

> And while we're talking about the BC/Fensa niceties of windows, let's not forget the insistence on those wee little nylon brushes that are slid into a routed groove...already to suck up water and rot your windows in a couple of years time. :evil:



A different view on brush seals could be. Position them where they don't get wet, if they do get wet they should dry out rather than trapping water behind them. I'll be using them on the windows I'm making, only time will tell.

I've started the Blog I mentioned, http://slidingsash.blogspot.com/
It could be useful, when finished, to beginners like myself, who are thinking about making their own box sliding sash windows. If only to avoid any mistakes I might make.

Andy


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## RogerS (6 Oct 2008)

agbagb":2g5hjo4k said:


> > And while we're talking about the BC/Fensa niceties of windows, let's not forget the insistence on those wee little nylon brushes that are slid into a routed groove...already to suck up water and rot your windows in a couple of years time. :evil:
> 
> 
> 
> A different view on brush seals could be. Position them where they don't get wet, if they do get wet they should dry out rather than trapping water behind them.....



How do you stop driving rain?


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## MikeG. (6 Oct 2008)

For the avoidance of doubt, an escape (or emergency egress) window should be a min of 450 x 450 clear opening with a min area of 0.33 sqm........the effect of which is that the minimum opening becomes 450 x 750. Remeber also that the opening (not the cill height) should start at or below 1100 above finished floor level.

The clear opening includes the thickness of the casement.......eg if the opening is 500 wide, and the casement opens to 90 degrees and is 60 wide, the clear opening will be 440 and so non-compliant. 

I appreciate we are talking sliding sashes here, but incomplete advice has a habit of being used out of context!!

Anyone still awake?

Mike


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## agbagb (6 Oct 2008)

> How do you stop driving rain?



As far as I tell from TRADA advice, labyrinth as much as you can and have a void area behind the gap before the seal. The void area will lower the air pressure and drop any water. As long as the seal is good, water shouldn't be "sucked" in to the seal.

That's the theory, I'm hoping it will work in practice 
Andy[/quote]


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## RogerS (6 Oct 2008)

agbagb":3uv2t293 said:


> > How do you stop driving rain?
> 
> 
> 
> ...


[/quote]

I hope we'll see lots of WIP pictures!


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## agbagb (6 Oct 2008)

I'll be testing the design with the first one of eight. I'll let you know how it works out in practice.
Andy


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## JFC (6 Oct 2008)

I would wedge those tenons and change the dovetail for a haunched mortice and tenon if i where you , also wedged . I'll probably get my IP thingy blocked again so if you want more info or to talk it over then quite a few here have my details . It looks like you are doing a nice job , i'd hate to think it wont last because of a few small details .


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## BradNaylor (6 Oct 2008)

JFC":1ns2xmwb said:


> I would wedge those tenons and change the dovetail for a haunched mortice and tenon if i where you , also wedged . I'll probably get my IP thingy blocked again so if you want more info or to talk it over then quite a few here have my details . It looks like you are doing a nice job , i'd hate to think it wont last because of a few small details .



How did he get back on?

He didn't even have to change his name!

:wink: 

Dan


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## JFC (6 Oct 2008)

Because i'm a nice baddy :wink: 
I might do a " how too " on rad covers soon just for you  

Byeeeeeee ..........


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## BradNaylor (6 Oct 2008)

I might do a 'how to' on spelling just for you.

:lol: 

Dan


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## JFC (6 Oct 2008)

Too . To a greater extent than is possible . My spelling is correct :lol:


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## MikeG. (6 Oct 2008)

JFC,

I am being a pedant today, but you are wrong and Dan is right. "How to" is correct......."how too" would be wrong unless you meant "how also". Sorry!

Mike


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## BradNaylor (7 Oct 2008)




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## agbagb (7 Oct 2008)

JFC":g9qnq5ea said:


> I would wedge those tenons and change the dovetail for a haunched mortice and tenon if i where you , also wedged .



Good thoughts, thanks. 
I was thinking a tight tenon without wedges would be good enough. I was concerned though that being so tight it would wipe the glue off on final assembly (I'm thinking of using PU). Can you enlighten me about use of wedges? Wedge(s) at the end(s)? Fox wedged?

Haunched M & T instead of dovetails. The bottom sash meeting rail is only 18mm deep, so if the tenon was 10mm would a haunch of 8mm leave enough material at the end of stile. The top sash top rail is 28mm so I think I should be able to fit one in there.

I only went for dovetails as that seems to be the traditional construction.

Any advice greatfully recieved.

Andy

PS. I posted too much on my blog yeserday and it's being reviewed for spam.


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## opener (7 Oct 2008)

Jfc is right about wedging the tenons but the correct joint for the meeting rails when there is no joggle horn is as shown here: 

http://books.google.co.uk/books?id=Nx2R ... &ct=result

(needs modifying slightly for large double-glazing rebate)

Cheers
Malcolm


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## agbagb (8 Oct 2008)

Thanks Malcom, Thats the kind of info I researched that lead to the dovetails Iv'e used. 
Do you know why I should use wedges on the tenons? Sorry if I'm sounding like my son - Why? Why? Why?
Andy


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## opener (8 Oct 2008)

Hi Andy
All joinery tenons are wedged to keep the joint tight should the glue fail over the years, belt and braces.
It's also convenient when assembling the sash to knock the wedges in and remove the cramps without waiting for the glue to dry.
Cheers
Malcolm


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## agbagb (9 Oct 2008)

Thanks Malcom, 
I like the look of "Fox wedges", (thin wedges into saw cuts in the tenon) so i don't have to taper the sides of the mortice. 
Andy


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## opener (9 Oct 2008)

If you have a morticing machine it is a doddle to taper the mortice sides. 

Make a wedge 10-12" long, the same thickness as the stile and the same angle as the glue wedges. 

Drill the face side of the mortice normally and put the large wedge underneath the stile to mortice the back side. Hey presto - angled mortice sides.

That is the traditional type of wedging in windows and doors rather than cutting into the tenons. (Don't know if it makes it any tighter though)

Cheers
Malcolm


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## agbagb (10 Oct 2008)

Cheers Malcolm, With that tip it's going to be so quick to do, I'm going to find it hard to justify not wedging. Even if it is "just to be on the safe side".

Andy


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## agbagb (24 Oct 2008)

Ever the reble, only one way to find out, I've fox wedged the tennons. I'll be kicking myself if they fail before I've popped mi clogs.

Andy


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## agbagb (25 Nov 2008)

Just an update, all the woodworking for my box sash now finished. 
Just painting, I'm trying holkam linseed paint, glazing and fitting to go.


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## agbagb (2 Jan 2009)

Another Update.
The window is in and working.







A few little design mods and I'll get on with others.

Andy


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## joiner_sim (3 Jan 2009)

Looking good. :lol:


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## agbagb (6 Feb 2009)

RogerS":1k9rkbrq said:


> agbagb":1k9rkbrq said:
> 
> 
> > > How do you stop driving rain?
> ...



I hope we'll see lots of WIP pictures![/quote]

We've had a few weeks of weather up against the window. I've slid a piece of paper up the side, so far the brush seals have stayed dry.

So Far so Good.
Andy


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## agbagb (18 Nov 2009)

In to the second Winter, Still no problems..... apart from a weight cord stretching, should have tied it with more clearance. Livin and Learnin.


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