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I'm looking to floor the loft of my house for some light storage (mostly decorations and clothes) and have a potential idea that would not only give a better finished result but also save some time and materials in the process.

Through research and discussions with friends with similar houses I am aware that I should use loft legs to raise the flooring I'm about to install above the insulation; as it works less efficiently when compressed.

However, unlike the lofts I've managed to find so far, my rafter ties* appear to be uncharacteristically low, to the point that placing loft legs under them would provide little additional space and would actually make moving around the loft more difficult as there would be rafter ties to step over every couple of steps.

The sources I have found so far discuss fitting flooring, via loft legs or directly, to the bottom most support of the loft, my question is, would there be any additional concerns with installing the flooring onto the rafter ties instead?

*I believe this is a trussed roof but that these components are still called rafter ties, apologies if my terminology is off. Here are some pictures to hopefully better demonstrate my question and concerns. Edits are welcome and I can supply more information as needed (such as measurements, clarifications or further pictures).

The main frames of the roof, showing where I hope to install the flooring:

The exposed, bottom most support, where most sources discuss installing loft legs:

How the rafter ties are connected to the trusses:


Additional pics as requested in comments:

Short video, panning left to right and up and down:

https://youtu.be/P6TIX-2g18c

Inside the loft, looking left:

Inside the loft, looking straight on:

Inside the loft, looking right:

Loft access hatch from the hallway below:

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  • Neither those ties, nor the gussets, nor the members to which they attach are designed for that load. I won't tell you not to do this, but use good sense. Spread the weight and don't go overboard. Any modification will void any warranty and possibly your homeowner's insurance policy.
    – isherwood
    Aug 8, 2022 at 21:20
  • "but use good sense" - I'll certainly be doing this, but I'd rather not rely on it! What's good sense for me may be an obvious mistake to others, hence I'm here! It is safe to assume good faith though, assume what I'm going to store is light items and it will be policed strictly. Aug 8, 2022 at 21:50
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    While you may strictly police the storage use to "light items", A) A lot of "light items" can become quite heavy, and B) The next people in the house may not do so.
    – FreeMan
    Sep 8, 2022 at 15:03
  • Agreed! Wondering how the OP is doing with this one :)
    – MiG
    Sep 8, 2022 at 15:10
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    I don't think anyone is not assuming good faith here! Keep in mind that frame challenges are important when safety is concerned. We just want to make sure the result both is and stays safe. Hope you (and others that may have a similar question and read this) find the discussion at least useful, and we're looking forward to hearing/seeing what you eventually constructed :)
    – MiG
    Sep 9, 2022 at 14:05

3 Answers 3

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I'll be honest. Shortly after building our garage nearly 30 years ago, my wife and I maneuvered the largest sheets of OSB we could squeeze up onto the bottoms of the rafters and have slowly been accumulating crap up there. We're at the point now where there really isn't any room to add anything new. This hasn't been light stuff like Christmas decorations - we've got boxes of papers and other things that we no longer need (as evidenced by the fact that none of it has been touched in ages, but that's a personal issue to deal with...).

These rafters were not designed for storage/living space, as they're all diagonally braced like yours and the bottom chord is only 2x4. I haven't put a straight edge/string across them to look for any sagging, but there have been no obvious issues over the years.

While I've learned a lot in the ensuing 30 years and I wouldn't recommend that anyone do what I've done, I will post this as anecdotal evidence that storage in rafters not designed for storage will not necessarily lead to immediate collapse or calamity.

Disclaimers:

  • I am not recommending that you store stuff up there.
  • I cannot, in any way, guarantee that your insurance company won't fight a claim should something bad happen.
  • I am not guaranteeing in any way, shape, or form that you'll have the same experience that I've had.
  • We tend to be overly cautious here in making recommendations simply because people will tend to exaggerate the bad and cut back on the good simply because "doing it right" takes more effort, and "doing it wrong" is almost always easier in the short term.
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That last photo shows those ceiling joists being mounted for roof stiffness (which is what they're intended for). Without significant additional strengthening however they would not be able to hold any significant loads. As these cross beams are effectively just hanging down from the rafters with those rafter ties, anything on there would solely rest on those metal pins.

Although you may plan to only store light materials there, I would be very careful mounting anything that even remotely suggests it could support both a person and additional loads. Keep in mind that you may not end up being the only person rummaging around up there, either family members (for example future adult offspring helping out to get something) or if you sell the house, future owners.

As they can still hold light items (for example packs of insulation materials, boxes with clothes and whatnot), I would alternatively opt for denser spaced, thin ceiling joists perpendicular to the roof, with regular openings (say two joists closed, one joist open, and the perpendicular joists spaced 30cm apart) that you can reach with a ladder. Example (top down):

enter image description here

These will be able to hold objects, boxes and packs while in no way suggesting that a person should crawl up there. This will also keep the structure completely visible so you can see any future wear and tear on connections and beams. I might additionally consider stiffening those connections a bit more, they will after all be carrying a higher load than they were designed for.

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  • "that you can reach with a ladder." - I like the sound of this set up, but perhaps it is not clear from my question but the loft is entirely sealed except for a single access hatch, so you couldn't leave gaps to access via ladder in this situation. Could work for others though, and I like the way on conveying not to stand on it to future users. Aug 9, 2022 at 11:50
  • Alright :) I'm quite concerned about load bearing capacity though (and unaware people who might climb up there in the future and load it up with heavier things). What does the structure as a whole look like, do you have a photo of the room that access hatch is in? Would it be possible to strengthen it in different ways?
    – MiG
    Aug 9, 2022 at 11:56
  • Give me a few minutes, I'll go grab a few more pics and edit them into the question. The room the hatch is in is the hallway at the top of the stairs, I'll get one of that as well but I don't think it'll add much! My preference for future people (including future me!) would be to paint, as a warning, directly onto the flooring the maximum weight that should be put on each board, and a conservative value at that. Aug 9, 2022 at 12:06
  • Edits made MiG. Aug 9, 2022 at 12:38
  • Thanks! Well... The floor underneath doesn't give you much options for additional support. As mentioned, my main concern is those rafter ties. Those wooden beams aren't supported by the trusses but rather 'hanging' off of them. They might support a person with some stuff, but considering the rafter ties are hammered in place, it's not exactly a long term secure connection that could withstand additional dynamic loads (i.e. a person rummaging around).
    – MiG
    Aug 10, 2022 at 9:38
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First be aware, what ever you store there it will be exposed to very high temperatures (from heat accumulation). Sometime up to 30 higher the outside. I had some Christmas candle there and they all melted.

Those horizontal rafters have weight limit. I installed floors in my attic, and I weigh 200 pounds, and all went well.

I used boards that will cover 3 rafter spaces, thus minimizing cutting. The cheapest one I found were fence boards.

One wrong step during installation and you will fall through the ceiling.

I would add some screws to those metal ties.

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