Measuring for new windows. How exact?

akira181

I'm getting quotes to get my windows replaced and I'm surprised at how rough they are with measuring windows. It's taken most of them 15 minutes to measure 9 windows. Most of them didn't even bother opening any of them.

Out of 6 quotes, only 2 had measurements included and they were different. Usually by 2cm in width, although one had a 20cm difference in height, which I'm wondering if that's a typo or not.

A couple said they would come back and take detailed measurements if I decided to go ahead with them, which makes sense. The one I was leaning towards said his original measurements are enough, he just had to order them and arrange an install date.

Is this normal or should I insist they come back to take more precise measurements so I get a window that fills the gap and I not end up with excessive PVC trim?

daivid

It is unlikely any of your openings are perfectly plumb or square so gap filling of one form or another will always be necessary. Within 2cm seems close enough as the frame is going to end up recessed. When it comes to excessive trim that would be a conversation to have with whoever you want to install, along with the widths of the frames and subdividers, and how many panels bigger windows will have.

stuart45

They should take measurements top, middle and bottom, as it can vary between the jambs, so the smallest is important. They should be able.to get closer than 20mm accuracy.

Doozergirl

stuart45 said:

They should take measurements top, middle and bottom, as it can vary between the jambs, so the smallest is important. They should be able.to get closer than 20mm accuracy.

This. 

It's fair to take an approximation for pricing purposes, perhaps, but the standard measurement should be 5mm less than the smallest of three measurements that Stuart mentions. (As well as left, right and centre)

If you are asking someone to supply and fit then they are responsible for getting it right.  

TELLIT01

It was years ago when we had ours done, but approximate measurements were taken for pricing purposes and then somebody came to do accurate measurements before the frames were manufactured.

Albermarle

TELLIT01 said:

It was years ago when we had ours done, but approximate measurements were taken for pricing purposes and then somebody came to do accurate measurements before the frames were manufactured.

Yes same for us, and they had a good look at the overall state of the walls, lintels, outside stone sill etc on the second visit.

gm0

Replacement windows.  Ugh,  Condolences.

Entirely normal to measure fast and approximate for a pricing config quotation.  And to do it properly only once an order is incoming.  Size is going to move by a cm or two.  So the "supply" element isn't going to shift appreciably in cost/price (for that reason - other decisions might move it).

For windows you can reach (or open). I would advise you to measure and use that list of measurements to check the "order" configuration carefully if/when they send it to you to approve it. Measure vertical height at reachable points left/centre/right. Exterior brick work.  And width at top/mid/bottom.  Record all and highlight smallest.  Keep that list to check they haven't screwed up data entry.  Laser pointer tape measure makes this much easier.  This means you "know" what the size of the holes is.  The size of the to be ordered windows will be close to this but slightly smaller.

Installer may send order config for sign off to be clear you have "agreed" the spec - for things like, 2g/3g, obscure glazing, bedroom egress versions, trickle vents on the list of windows.  They should use their expertise to know regs and what *must* be done on a given window (the fire safety egress stuff especially). But they may show it to you to avoid customer "surprises".  Check it carefully on the order to manufacture version.  It's worth it.  Yes - I know this is having a dog and barking yourself. If the proposed windows are bigger than your measurements (measure, keying error) or start to be a lot smaller than your aperture measurements (ditto) - it's time to ask some more questions - the gaps (half each side and top/bottom) are getting larger.

It is normal for windows to be made slightly smaller than the apertures at narrowest/shortest side and for not quite square aperture to be filled around. 5-10mm gaps around would not be surprising.  No gap or a lot more would invite questions.  There are many different window edge weather sealing and air seal technologies for different structures - compriband tapes to the exterior, expanding foams (interior), various silicone sealants.  Some of these are more expensive (supply quote) and time consuming for the installer than others.  And also better and worse for longevity and thermals for you.  It is important to understand what you are getting.  It needs to suit the windows selected.  And your structure.  And your budget. Interior impact varies with what you put in as as well.  Sadly you need to know enough about this or you are "in their hands" be they professional or less so.   Attaching a couple of brackets, Hack away some plaster for the brackets.  Drive the screws and a squirt with the "glue" gun around the outside edges. All done. Next.  Replaster left as an exercise for the customer.  That is the cheap (and not very cheerful) method.  Their incentive is a fast as possible for the agreed price.  You may wish to agree the installation detail and be a bit more specific.  Installers are not joiners or decorators and hate getting involved with complex interior make good. Finding one willing to just do it all as a project - can be quite hard and expensive.  Choose your pain. Getting the team on site on the day to follow what was agreed rather than leave it unread and work to their own personal default method - is another separate frontier of pain.

What they can't afford to get wrong is to order windows that are too big.   As they will need to be remade.  And the factory want paying twice so the job is now lossmaking.  A few mm of a single lumpy brick is a few seconds grinder job - but bad measurements and >25mm too much window means "go again".   So their incentive is to go for accurate erring towards too small.  But *you* don't want them too small either.  As the gaps will be uglier and the thermal performance may also start to suffer.  So bodgers "knocking a bit more off the measurements to be safe" isn't what you want either.  Hence measure and check what size gaps are going to be (assumes the factory makes what is ordered).  You want as close to aperture size as the installation method tolerance requires.  Many horror stories arise where an error is made and a window is "too small" but it is fitted anyway and the job is over.  Invoice lands and a lot of shrugging goes on thereafter about doing anything at all about it.

Know what you are doing about cills - life expired windows may have rotten wooden cills.  If anything is - or is going to be - underneath the window these are linked measurements.  A good time to know is "pre-order". So check cill condition (if timber) and falls and water pooling on any brick/stone structure and think hard about what to do about it.  Might be like for like.  Might not.  Easy.  Pour some water on the window face and watch.  Does it pool/drain.  And is the wooden window sat in it.  Is that why it rotted (bottom up rotting would be a clue) vs general neglect and poor softwood.

If structure - walls/cavities, depths, mounting points is uncertain - it can be super helpful to remove a window temporarily and take a good look. A couple of hours work to pay for but if it changes the approach and the order before finding out x10+ - worthwhile   I nearly had an ordering the wrong windows disaster which was avoided ONLY by doing this.  If the contract terms don't put these hidden structure risks with the installer (and they may well not). It is obviously not going to be a topic they want to raise pre-sales at competitive quotes stage. If it shows up. Sorry guv. Here is the bill.  Nobody could have foreseen etc. T&C.  Tough break mate.  A 10k mistake perhaps.

Caveat emptor and happy trails

akira181

Doozergirl said:

If you are asking someone to supply and fit then they are responsible for getting it right.  

I understand they're responsible for supply and fit, but the only time they'll willingly take responsibility is if the window is too big to fit and they can't force it in. 40mm or 50mm too small, most will still fit it and claim that's the way it's supposed to be. 

I've had a contractor downright refuse to admit they made a mistake before despite it being blatantly obvious and it took legal action before they would admit it and reduce the final invoice by more than half to cover costs to make it right. Really want to avoid that level of trouble again.

I measured the windows myself and my measurements matched the preferred quote within 5mm (the other quote had one window +20cm/200mm too tall). All measurements taken from the inside only. Mine were generally on the lower side of the scale, his measurements on the larger side. I guess he knows what he's doing, only took me 15 minutes to measure too so makes sense that the pro's are quicker.