Double hung timber sash windows look great on older or period homes but they can be draughty and offer poor thermal performance, assuming you want to keep them and not replace them with modern double glazed units[we wouldn’t unless they look the part!] then there are a number of things to keep you eyes open for when you are viewing, all of these defects will reduce the life and performance of the window and require expenditure to correct –
- You need to check the sash cords are present, if they are pull them without opening the window – you should feel the weight on the end. If you don’t or the cord comes loose then the sash cord needs replacing. It’s not a difficult job but is fiddly and does need the access slip on these of the box to be opened and possibly the sash to be removed which may need the closing beads to be taken off and then refixed. Windows usually need redecorating at least in part after this work.
- Open the sash window and check it stays up. If it slips down it has probably been reglazed with a thicker glass which is heavier than original. If the original sash weight has been used it may not be heavy enough to counter balance the window.
- Have a look for the tell tale signs of condensation, because these windows are single glazed they very often suffer more than double glazed and modern units.
- Check that all the ironmongery is present and that the sash hasn’t been painted shut and is free running. Quite often everything goes out of square when windows are badly maintained and this can affect catches – we’ve seen them adjusted with lolly sticks, cardboard and all manner of Heath Robinson solutions.
- Remember that ground floor windows and other accessible windows almost certainly need key operated locks to comply with most insurers minimum requirements. Not a difficult or expensive job in itself, say £60 a window. But if you have ten windows then that cost mounts up.
- Outside have a look at the frame and the sill. If it’s badly maintained you may well see some decay. A key or screwdriver can be useful to jab into soft timber. This will probably be wet rot and will need cutting out and replacing. Look also for pieces of timber scarfed in and for metal L brackets on the corners of sashes, all indicators that the units may be past their best and may need expensive attention.
- Look for any glazing below 600mm, these days there should be safety or toughened glass but this wasn’t the case a hundred years ago. We strongly recommend adding fall protection or changing the glass. (see above as the sash weights may need to be changed)
- Check that the glass isn’t cracked, if it is it may need replacing. Check that all the putty is OK, repairs here may mean external decoration.
And finally, If the windows need replacing then current building regulations require them to be double glazed, this can be done to new sash units but they will be thicker than the originals and probably stick out into the room by about 30mm, there’s not a lot than can be done to overcome this. The modern units though will look appropriate, be thermally efficient and have proper draught exclusion. Work on around £800 per window on average for a double glazed double inbox sash with hardwood sill. It’ll go upon don bait depending on size and location.
Remember if your home is in a conservation area or listed you should consult the conservation officer and planning department at the local authority as planning consent may be required.
Need more advice, a building or property survey or windows reported on? Collier Stevens can help across London and the South East, single defect reports are usually in the range £300 to £400 depending on the location and type of defect.