I've been asked by my better half to do a full length lid on our window seat. It would be 2400mm long and 580mm deep, 18mm baltic birch plywood which the provider says would weigh approx 22kg. Checking on http://theplywood.com/weight says it would be 16kg so quite a range.

I'm trying to figure out what kind of hinge/openers would assist with opening it so it could be done 1-handed, but also be able to hold it open and provide a soft close. I'm guessing some form of piston as that's what I've seen on car bonnets (hoods). I'm assuming that the length of the lid would cause an issue as a hinge at either end might not be enough. It may be that this is a terrible idea and I should go back to researching split cushions that would make her happy.

  • Are you sure you really need the seat to be one long continuous piece? It's much more common to split a bench top into two or more sections to make raising the lid easier, and it would remove the need to look for any sort of specialist hinge or a soft-close mechanism. These tend to be significantly expensive, in contrast to standard hinges which can be dirt cheap and are far more widely available (basic hardware store purchase for most people).
    – Graphus
    Commented Sep 9, 2018 at 14:07
  • The better half wants to keep it as a single piece for aesthetics. I'm not one to cross her these days!
    – beirtipol
    Commented Sep 10, 2018 at 12:11
  • Fair enough, many of us have to work with similar constraints! I have found however is that once the price comparison is presented the modified plan can be much more warmly received ^_^
    – Graphus
    Commented Sep 10, 2018 at 17:10
  • 1
    By "birtic balch" did you mean "Baltic birch" or something like that? Commented Sep 11, 2018 at 7:45
  • You know when you've been looking at a word for so long that you can't tell if you've misspelled it? :) (Updated the question!)
    – beirtipol
    Commented Sep 11, 2018 at 16:24

2 Answers 2


There is actually such a thing as a Bench Seat Hinge but the heavy duty ones only seem to take up to 12kg. You might be able to find one that'll take more weight, but my suggestion would be to split the seat lid into two or three sections and hinge them individually (assuming your better half doesn't object to a split lid). If you're going to be upholstering them too that'll also add to the weight.

The soft close would require a Soft Down Support - there are a number of different options out there, and the support will actually take some of the weight off the hinges and you could then use a pair of more normal cabinet hinges per section.

  • 2
    Be aware that some of the 'soft down' supports are extremely finicky to place properly. (I have experience with the Sugatsune; I can't say if others are better.) If it was me, I'd take pains to build the box off the floor so you could get inside it to set the support. Commented Sep 9, 2018 at 15:20
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    Knowing the right terminology to search for was key! Thanks Wex and welcome to the site
    – beirtipol
    Commented Sep 10, 2018 at 12:13

I've had very good luck with torsion hinges. They hold the lid in place when it's opened and allow you to smoothly close it without slamming. And they have a minimal visual impact on the piece. They're slightly bigger than normal hinges, but it's hidden behind the lid.

You do have to have to know the weight of your lid, but in my experience the range of weights that will work is fairly wide.

  • Another wonderful rockler product that I'd undoubtedly get burned on with import fees to the UK :( I'm going to have to move across the pond. The more I get in to woodworking, the more I get frustrated!
    – beirtipol
    Commented Sep 11, 2018 at 16:28
  • This looks like a fantastic option, but @beirtipol - if you were to go this way, be sure to use their calculator. I did a quick conversion from metric to SAE and it came out at > 500 in/lbs of supported weight. You'd need a lot of those pricey hinges...
    – FreeMan
    Commented Sep 12, 2018 at 15:29

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