Scissor truss anyone?

I think I'll stick to open beam ceiling. Makes a triangle.

Just install a dormer

Very interesting. I have been considering a way to do this in a garage.

I’m shopping an old home right now where you can see plain as day the same considerations taken to make habitable space access into the old attic. There is an oddly shallow dormer on the rear roof that surrounds just the attic staircase, to add code-compliant headroom when reaching and exiting the top of the stairs. No windows in the dormer walls, just a couple of (leaking) skylights above.

That pressure is on one set of rafters actual load is spread over the length of the building.

Why not put in a switchback stair?

Hi Robin, have you got any info on fixing either end if the beam to the existing building and new gable end. Would BI need to see a pad stone on tbe gable end? Is the existing end fixed to diagonal wall plates in some way?

The beam doesn’t have to be steel. It just needs to be a sufficient beam which any Engineer would be responsible to incorporate the proper beam. Your test is not including the two end Support walls that hold up the beam so this test is irrelevant and not to be taken seriously.

Excellent video, very informative but.. It's a bit unfair with the "cowboy loft storage companies".. We do quite a bit of work in both truss roof houses and older hand cut roof houses. When we offer to do the job properly by ensuring there is more strength in the exsisting ceiling the cost goes up and we almost always loose out to other firms.. If we just offer the customer a timber raise and slap some boards on top we normally win the job. People only seem to care about how much it costs, wether or not it's safe doesn't come into it!! You wouldn't belive the amout of people we quote that say "cant you just nail the boards the the joists?" or "why raise the floor when you can just cut out of the joists for cables". Clearly we refuse but that's what we have to deal with with our customers. I've been in more truss roof houses than I'd like to mention where the owner, or worse, the actual builder, has cut through trussess to fit the loft hatch in then they complain that their ceiling has cracked!!! The market (IE the customers) push companies to do a "cowboy" job becasue they just don't want to pay to do it properly.

Sir regarding single point loading in a beam test would you please show me the area of bearing of of a timber in a timber testing.

??????....whats a steel ridge beam going to accomplish?

Use a spiral staircase.

Flitch plate 2x10 or 2x12 ridge depending on the length of the ridge and load on the roof or a lambeam ridge Cross walls or walls at right angles off the walls the birdsmouth ties into and collar ties also windbracing on the under sides of the rafters if its to be a covered rafter ceiling Decorative box beams could also hide high tension cables in some circumstances

You should also point out that you should never used screws to construct a roof because in a very short period of time they're going to snap with the little movement of roots

This experiment is kind of naff and in no way scientific, all your variables and scales are very incorrect and uncontrolled. The weight needs to be scaled and applied over the entire roof not just you pushing on the peak, roof timbers are normally deeper and fixed in a way to reduce flexing and rotation so the forces are directed differently. Most domestic traditional roof work is very over engineered so this isn't even a real problem unless your doing it yourself and dont know roof carpentry. If your making a small roof with undersized timbers say for a large shed then make your own trusses with ply gussets or gangplates and they will be good enough.

how many degrees does the roof

Collar ties. Duh

Hi Robin, would it be possible to have the model for this? Very infomrative.

No mention of fire safety at all? It's a different situation for a 3 storey house

I didn't kno that

Make a ridge beam instead of board and make it load bearing directly under each end. Solid beam like a sawmilled tree. Dovetail the beam and rafters together.

You would have to have a solid ridge beam completely supported and notch it and the rafters to lock them together where they can not pull apart. Never stick frame that but never say never altogether though.

Stupid. It doesn't matter what the ridge beam is made of. It's the strength of the rafters at the point of the ridge that matters and/or whether the walls are buttressed where the rafters rest on them. This type of "ridge pole" construction is absolutely not the way to make a vaulted ceiling except where the walls are solidly buttressed against spreading. It's perfectly fine to have 2x12 rafters overlap each other to form the ridge and have glue and multiple screws attaching them with blocking in between them to finish the ridge, but best practice is to have the vaulted ceiling located where the walls the rafters attach to are solidly buttressed against the spreading of the rafters.

Not quite sure how the steel ridge beam helps, is it because it transfers the load to the end walls (which are not shown in the model) ? Thanks

With so many (so obviously) opposed to the steel ridgebeam idea, and the meticulous well thought out and edited video regarding load transfers, you almost think that the creator is trying to teach the opposite point: that by removing the ceiling attachment and adding a laminated lvl or steel ridge beam can make the roof to wall connections weak and lead to wall-pushing

Your scale modeling with woodscraps is producing scraps performance.

Boy a lot of people have got something to say. Engineers trying to show how cleaver they are, people concerned with terminology or whatever. The fact is, rafter deflection is what is being demonstrated. Try doing this with appropriate sized steel and weld it at the top. No deflection and no wall spreading. Do it with appropriate sized timber and fixings of the collar tie and again, little wall spreading. There are very good truss rafter designs that lend veey nicely to vaulted roofs, look at most churches and many have stood for hundreds of years.

Hello what design program are you using

If the ridge is adequate to carry the load there will be no spreading. The rafters also need to be adequate because if they flex it will pull in on the walls unless the plumb cut and seat cut start to gap then there will be spreading. Straps over the top rafter to rafter and also a positive connection on the exterior of wall to the seat cut will also work.

Steel beam as you described will not transfer the load to the gable ends unless it is supported at the gable end, but a ridge beam with gable end support should do the same but cheaper. A structural engineer would need to determine that though. I have wondered if installing a, let's say 12" wide wall cap might counter the side load and flex. That could work by transferring the side load to the gable end walls. I am not the structural engineer though.

Engineered scissors truss from a certified factory will push out the walls also. Mine were a 24' span and did a nice 1.5" push out over time. To counter this I should have tilted the supporting walls in. Since the truss' are wood it may have exceeded the inward tilt anyway.

It should not take 6.3 mn to say where to place the tie

So much to learn here😂

The worry with Victorian roofs is that the nails fastening the ceiling joists to the plates rust through. Happily the nails they used seem to be high carbon cut nails and don't rot much. I used to add extra nails.

Surely you need purlins in any large valuted roof! That would stop this issue anyway?

No test with the solution?

What was wrong with the first solution? 2:32

Why not set the wall plate on a box section steel member that could interface between the plate and the wall itself. If the box section is sufficiently tied at each end and strong enough to prevent lateral deflection, that seems like an alternative to a steel ridge beam that would need a fairly tricky load transfer arrangement if for example you had openings under one or both gable ends. Just a thought.

Duuu

Toothpick framing is so outdated

may I ask which application/ software you use to draw ? very nice explanation! although in my (non professional) opinion, don't necessary has to be a steel beam but some "beam" to hold the load... thanks for the video 😉

How do you achieve a vaulted roof on a hip ended roof ?

?? how is the steel ridge attached?

Reinforced engineered trusses and your good

As a non-carpenter that video is for me incomplete without the demo of the steel ridge beam ! Sad !

thanks for the helpful video! just one question: 1:19 what is the 5 for? is this a constant number for every deflection calculation?

The single screw fixing at each end of Robin's collar-ties allows for rotation around the fixings themselves. No sensible carpenter would use just a single bolt to hold this connection. If the rafters flex/sag in time a bigger, stiff, properly connected collar will do a great deal to hold the rafters straight - heftier collars can really improve economically lightish rafters.

Do I need a steel on the front wall or can I build of the the internal with a 4x 2 wall plate?.

Solution post at each end and possibly the middle of the Ridge beam