Dimensioning a loft bed

[Kahuna]

The children are growing fast, so now we're planning a loft bed. I've made a first sketch (of course, the safety rail is missing, and we haven't decided on the mounting height).



The idea is to have two children (105 cm and 125 cm) sleep in the same bed with their heads against opposite walls. Ideally, we want the space under the loft completely free as a play area, meaning no post in the middle and a movable ladder that is not intended to function as support.

The material choice is pine. For a regular beam (or glulam beam), what dimension is needed for the specified span of 2870 mm? Assume an additional beam is mounted in the middle (parallel to the outermost one), is it possible to reduce the dimension?

 

[Thomas_Blekinge]

90x145 should be enough if you choose light slats. How wide should the bed be?
If you're unsure, you can easily hang it from the ceiling. This can be integrated with the guardrail.

 

[justusandersson]

It's mostly a matter of comfort. If you choose 45x145 C 24 for the front edge beam, even 2 fully grown men can lie there without feeling worried.

 

[Kahuna]

90x145 should be enough if you choose light slats. How wide should the bed be? If you're unsure, you can easily suspend it from the ceiling. This can be integrated with the safety railing.

The width will be about 1 m. I was thinking of using slats 22x95, which should work as light ones. I found a bunk bed from Jysk that is supposed to handle 90 kg, it had slats of 15x66 but that feels a bit flimsy. 90x145 is not a dimension I recognize and I get no search results. Do you mean 45x145? Hanging from the ceiling is absolutely conceivable, but I haven't come up with an elegant solution. Construction fittings are out of the question if they can't be concealed.

It's mostly a matter of comfort. If you choose 45x145 C 24 for the front rule, even 2 fully grown men can lie there without feeling worried.

One of us parents will probably crawl up and read a story, but with both it will be a bit cramped. How do you mean that comfort is affected?

 

[Thomas_Blekinge]

I mean 45x145

 

[justusandersson]

By comfort, I mean the deflection you are willing to accept. Håll r usually does it. 45x145 is probably optimal.

 

[windestal]

How do you think "for the future"? I think the total length of 287 cm seems too short to be a sustainable solution in the long run for two children. (Even if the construction surely won't break down.)

The children are growing fast and their combined length is already 230 cm. Since you don't lie with your head pressed against the wall, it will probably take about 250 cm or so. That leaves only around 37 cm (or 18-19 cm per child) before their feet overlap. Enough today for the end of the blanket, but in one or two years when they have grown further, there is a high risk that they will disturb each other when they move in their sleep (or before they sleep, even if they are best friends now, it could become troublesome later on).

 

[Kahuna]

How are you thinking "for the future"? I think the total length of 287 cm seems too short to be a sustainable solution in the long run for two children. (Even if the construction surely won't collapse.)

The children are growing rapidly and their combined length is already 230 cm. Since you don't lie with your head pressed against the wall, perhaps around 250 cm or so is needed. That leaves only about 37 cm (or 18-19 cm per child) before their feet overlap. Perfect today for covering with a blanket, but in one or two years when they grow further, there's a big risk they'll disturb each other when they move in their sleep (or before they sleep, even if they're best friends now, it can get more contentious later on).

I agree that it's on the shorter side, but we have limited space and the advantages of the freed-up area under the bed outweigh it. Overall, we think it will work for a few years while we plan an extension. They are getting better and better at getting along, they rarely sleep stretched out, and they sleep as deeply as Skalman.

 

[BosseHansson]

Maybe consider whether it should be possible to fit a proper bed base in it later. It might affect how you design it.

 

[Kahuna]

It's mostly a comfort issue. If you choose 45x145 C 24 for the front edge, even 2 full-grown men can lie there without feeling worried.

I ended up buying 45x145. I tried setting it on edge on two supports on the floor with a span of about 2.8 m. I stood in the middle on one foot and my partner measured the deflection to about 5 mm. You probably won't feel it. Thanks for the info!

 

[justusandersson]

I calculated it to be 3.8 mm in my previous calculation with a 100 kg point load in the middle.

 

[Kahuna]

I calculated it to be 3.8 mm with a 100 kg point load in the middle.

And I only weigh 90... We can say that's within tolerance.

 

[D09]

You have probably already thought of it, but why not beds that fold up against the wall?

That way you get the play area as well as space for two foldable 140 cm beds next to each other?

The link/image is just an example

https://www.baddsoffexperten.se/bad...tillbehor/liggande-sangskap-budget-140cm.html

 

[Thomas_Blekinge]

Even a loft bed can be made to fold up. I had one like that as a student. Then you can build two of them opposite each other, and during the day they can be folded up and suddenly you have an entire room.

 

[Onsalakorven]

You have probably already thought of this, but why not beds that fold up against the wall?

Then you get play space and room for two foldable 140 beds side by side?

The link/image is just an example

[link]

We have also considered this, called Murphy bed abroad but not so common here at home. There are ready-made kits on e.g. eBay to buy with all the fittings, etc., but it's certainly possible to build it yourself of course!