How to support a cathedral ceiling or vaulted roof
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- Опубліковано 25 тра 2022
- If you want a vaulted ceiling you will need to support the roof with a ridge beam. In this video a structural engineer explains the options for a cathedral or vaulted ceiling for a small single storey extension in the UK.
Demo on how a vaulted roof fails: • Demo - Does a vaulted ...
Calculate a ridge beam, step by step: • How to calculate a rid...
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*Disclaimer:*
I'm a chartered civil engineer with a specialism in structural engineering. This video is for entertainment and none of the things I say or teach in my videos should be construed as 'advice'. You should always have your designs checked by a competent, experienced, chartered civil/structural engineer. - Наука та технологія
This is a brilliant video explanation of the how to deal with the horizontal thrust in a vaulted ceiling, explained in simple lay-mans terms.
Well done Robin, great video. (from Chartered Structural Engineer +20 years exp).
Hi Robin: The Full height A-Frame without the tie is one option but you didn't explain the loading implications if the A frame was mounted on top of the brick returns. I see a lot of extension builds made in this way and it would have been instructive to hear your assessment of the two construction approaches.
Brilliant video Robin. Thank you for sharing your experience and knowledge with us. Keep going. Thank you!
Many thanks for your whole series of videos Robin. Clear, concise and very interesting. Please keep up the good work.
The instruction is clear and concise. I'll be looking forward to seeing your other videos from the other side of the pond. Just subscribed.
Fantastic!... Just about to alter a bungalow we've just bought. Very informative and helpful. Thanks!!
You don't need steel unless the span of the ridge beam is extremely long. You could use LVL's or Glu lams as well. You don't need a A-Frame at the end for support either. You can add support posts under the end of the beam and then size a header across the door opening below capable of supporting the load above.
Do not discount what is usual in the US is not always usual in Canada, the UK, Australia, Newfoundland, or even Hawaii. Each region has their own norms. I've worked in most of those. You would be surprised at the regional differences, what their code requires, what the building inspector expects to see, even what materials are available.
@@Sailor376also, I realize there are different codes or requirements for different areas but the materials strength doesn't care where in the world you are located. It's strength is the same here in the US as it is on the other side of the world. It's availability could be an issue but it's strength is not.
@@jtltet I agree with you on this. The video is a general guide and should not specify the material. I built a similar roof and used a timber ridge beam. You then can use it between the rafters rather than under them.
Also on a small roof you can simply put diagonal straps (from end of ridge to middle of wall plate) to take up any push or have a cross tie at the top of the door level to make a triangle to then put a gable window in.
Very simple explanation and nice model
Thoughts are
Excellent design and fantastic video presentation
This channel is a hidden gem
In Ireland rural architects just draw pictures and give clients a design that requires a thorough structural appraisal
But having received planning they become aware that the additional costs are prohibitive and in some cases houses are at subfloor level before they realise the need for goalposts or windposts
Structural design should be costed by a QS at a preliminary stage and a compulsory assessment included within the architectural design
Thanks for the content !
In the US, this can happen as well, but the proper procedure is that the architect works on preliminary structural scheme, and they should have the knowledge to do this, and then develop it with the engineer. This is beyond "preliminary" stage usually, but where there is a need a preliminary pricing phase can be introduced. Here is the problem. Everyone needs to be paid, so the engineer is not brought in until a preliminary design is accepted by the client. Then there is a lot spent on design before the calculations are even done. Most contractors will not want to get involved in pricing either, until a full set of plans is available. Architects just don't have the exposure that a builder has in understanding costs, but some grasp of costs will help. A good architect is just as good at smashing client's dreams, as realizing a project that they actually can afford.
Hi Robin your videos are excellent very informative keep them coming,
Thanks
Mark
Thanks for spreading the word about "spreading". I see many houses that people have remodeled without regard to basic structural standards.
Thanks my friend. Spreading the word about spreading is my mission.
That's why we focus on ensuring a higher strength AFTER the remodel than before! I see so many DIY and even professional contractors who don't really understand loads.
Very helpful structural information.
You can also have deep rafters so that if you want to expose a part of it you can and then put a gusset plate at the arched ridge area. Also use a metal strap at the wall for l2 and l1 forces and double the stud at that bearing area.
Another good video. Thanks Robin!
Thank you 🙏 I was actually looking for a way to bring more light in the lounge and this is a brilliant idea.
A 3D model of this example would be great. I would love to look at it closely.
Thank you one more time for your work and your channel.
From an automotive engineer who Loves the Truth 🤗 (I’ve shared wholeheartedly your video with regards to the attributes of a civil engineer … the Love for Truth)
Thanks Florin - that's great to hear!
Great video Robin. Cheers.
Excellent video. Well explained. There are other solutions., such as steel A frame sat on brick pillars and this might be better if you are modifying an existing building.
BRILLIANT!! Clear and concise explanation, definitely makes structural engineering look easy. Just a couple questions, 1) Would you need a box frame/goal post frame between the main house and extension to make a through lounge or would you install a beam? 2) Any plans on showing how to calculate a box frame or goal post frame in the next videos? 👍👌
Hi Lee. You could use steel beams if there is sufficient masonry either side, or alternatively us a goalpost frame to make a larger opening.
i have to say was not expecting you to rotate the ridge detail.. Autocad even Autocad Architecture cant illustrate such clear detail.. came across your brilliant site today whilst reeducating myself on LTB restraint held in position but not restrained in direction .. it appears that some engineers give differing expectations on an allowance.. i tend to sleep better knowing i have a beam supporting a unforgiving load yet a low moment.. brill website thankyou
Thank you for the great idea using the steel beam
Great videos Robin, could you possibly do a video on converting the loft space (perlin) into a mezzanine for a small bedroom. Looking at different options to increase floor space without having to extend.
Excellent explanation!
Hi this looks great as I am looking to do exactly this to my home extension so if I can download this that will help me greatly, thank you for this great detailed informative vid.
I am currently designing a ridge beam for my own DIY extension. Preliminary costing for a 5m span ridge beam supporting a 6m wide roof suggests that a steel I-section is cheaper than a C24 timber beam. However, when I add the additional timbers required to fix rafters to the steel beam, the costs work out about the same. I am inclined to use a timber ridge beam because it is more user friendly than steel. I will look at flitch beams before I commit.
Laminate your own beam out of 9"x2" and rips of 3/4" ply or OSB. The other option is a gluelam beam, 💪🔨🇮🇪
I am currently designing a ridge beam for my own DIY extension. The ridge beam will be supported by the house wall and a steel shs column at the gable. The gable column will transfer a significant amount of the horizontal wind load on the gable to the ridge beam. In a normal roof, rather than a vaulted roof, wind load would be carried down to the walls via diagonal bracing at the rafters or by diaphragm action of the ceiling. My question is, how do you brace a vaulted ceiling against horizontal wind load? My gut reaction is sarking boards.
Nicely done, enjoyed that.
Thanks Eoin 👍
Interesting and informative. Thanks
Lovely work
Thank you Robin
Very clear awesome video
What a great video, thank you for that
Extremely helpful.
Only reason to do it that way is for a fully glazed gable. Otherwise it's entirely too expensive with too many workarounds. For the simple door opening that was there initially, fastest and cheapest would either be a framed and skinned gable, if wooden structure, or precast reinforced concrete with a recess and pressure plate, which would let you get around all of the scaffolding and thermal bridging and whatnot such things bring with it. Cast and reinforced tile beams are an option too.
Great video. Thank you.
Nice, pretty collar ties. Or a properly sized glue-lam supported at each gable by a king post.
This is the wackiest thing I’ve seen this week..
@@sumerfun01 As in you don't think that is a sound way to build? How do you think we build free span A Frame style homes in high snow load areas in one of the most heavily regulated building standards places in the world: Lake Tahoe,California.
Brilliant videos very informative 👏 would you mind doing a video expanding on cross bracing loft beams especially when it's become Very common for most of us using our lofts as storage space. Thanks
Thanks for your video. I'm not in the trade, but I want to build a small rectangular building (1,800 square feet), probably in Virginia, USA. I can now give this design concept to the architect, which is now an option. I suspect the I-beam might be too massive, but it's an option.
Great video! Thank you. We are about to do a similar job in our house but the single story extension is split into two rooms by a stud wall under the ridge beam. Can you suggest where I can read up on calculating the load that the roof structure will apply on that wall if I were to extend it upward to do the job of supporting the ridge when we remove the ceiling? Thanks!
Excellent video thank you...
Very well explained, Thank you. /Micke
@3:07, when you connect the two rafters together at the ridge board, the reaction forces become essentially internal forces which cancel each other. When you don’t connect the two rafters at the ridge board, the reaction forces become external forces which cancel each other while compressing the ridge beam only when the two rafters are symmetrical about the ridge beam. If the two rafters are not symmetrical about the ridge beam, the external force at the rafter supports are not equal, hence, won’t cancel out.
See my explanation here: ua-cam.com/video/BtsZk0UR2EI/v-deo.htmlfeature=shared
Interesting stuff. Can you not use the structural I beam as the ridge board with the roof rafters connecting directly to the web?
Thank you for sharing this video Robin. I think I would rather not have a vaulted ceiling. I didn't know it added extra stress to the walls.
Glad it was helpful! As long as you have a ridge beam (supported on the gables) there is no outward force on the walls
Nice video. Is the red frame a "moment frame"? How is the beam on the other side held up? By the wall of the larger building?
Excellent Video, very informative.
I am doing a building course at TAFE NSW and I am interested in learning about Portal frame construction for residential buildings.
Would you be able to make available in DWG format the steel beam and A Frame, please, so I can play around with in Archicad?
While I have you there, can you tell me, what is the maximum span one can have with cathedral or Vaulted ceilings, without making it price prohibitive?
Thank you,
Franco
I like your videos very well explained
thanks for a great video have done this without the steel as l have not opened the front but l am using 5m rafters with a steel ridge beam should l use a perlin on 9x3 rafters at 19 degrees thanks Loll
Hi Robin, might you be able to cover the creation of a vaulted ceiling like this in a bungalow with existing ceilings and a traditional trussed roof structure, please? (Ignoring the costs and in search of a "wow" factor!)
Great explanation to the layman - would an overhang be possible here above the patio doors?
Thank you for this video! Exceptionally helpful. One question, you mention that with the beam, there is no horizontal load on the walls. With the rafters supported at the ridge, is there no moment about the ridgeline and a horizontal load inward on the walls? I have a small shed I'm turning into a home office. I want to vault the ceilings, but I don't want the walls to pull in, or fall out, on me. ha! Thanks!
you can use LVL's or glue lams for your ridge as long as it is point loaded on the ends. I did 26 feet with a 3 ply glue lam. The only disadvantage is the point load, but we put windows on each side.
@4:10, each rafter is simply supported at the steel ridge beam and at the wall top plate. Due to the inclined orientation of the rafter the rafter will have two horizontal forces at each end as well as two vertical forces.
The rafters are connected at the ridge, so horizontal forces cancel out.
@@RobindeJongh ::: in your example, you removed the wood ridge beam and installed the steel beam instead.
It's a wooden ridge board. It takes no load and is just designed to connect rafters to.
Thank you.
Or, use engineered trusses. The bottom won’t be quite as vaulted but will still give that effect.
thank you for the video. can you tell me which software you are using?
Tks for this video. Curious to know what software you use?
Great explanation of forces in action. Did you make the 3d model available for download? It looks like a great tool
Ive vaulted the ceiling in my bathroom. I have collar ties in the ceiling and underpurlins supporting the rafters. I put a beam along between the two end walls and then have struts supporting the underpurlin. In your example when you took out the ceiling joists, if there were collar ties on all joists would that suffice? It would be a barn style ceiling as apposed to a cathedral type you show but just wondered if that would satisfy the equal and opposite forces pushing outward on the external walls?
Hi Robin great articles you provide
I am considering a flitch plate ridge beam to form a vaulted ceilings
The room is 10m x 4.2 don’t want to show any steel work and considering using flitch beams rafters to support flitch beam ridge if possible (possible 4 )
The flitch beams rafters would be like a Inverted v A with out the tie .plates welded
at ridge. if I design a flitch beam across the width horizontal 4.2 with a point ridge load would this work
And transfer loading to wall plate ?
Regards Dave
.
What a great download. Is it available?
Thanks for the great video's Robin, they are really informative. I'm currently designing the restoration of my bungalow and wanting to have a 2 story vaulted ceiling one end as in your clip but then have 2 bedrooms upstairs the other end split by the ridge with glass gable, would you use the same system the other end or rest the steel on a centre peer?
Hi Rick. If it is two storey height I would advise getting a structural engineer involved, because building regs (strangely enough) only apply to masonry that is single storey and then restrained by floors and roof.
Yes if would be great to be able to download these models.
Im switching to half of a cathedral ceiling in my garage to make a loft instead of the current attic. I'm just going to be tying the rafters together up higher and then vertically supporting the remaining rafters to the headers. Should work. if not, then I guess it wont lol
Hi Robin recently discovered your channel and its brilliant, do you have perhaps have one on steel gusset to timber bolt design video.. That shows how many bolts perhaps to counter act X bending moments or X forces
I don't have that video topic, but I agree that would be a good one to do. I'll keep it in mind!
Great clear explanation. 👍 Don't mind the nay sayers because I am sure that they can't even push a nail in soft butter 😬
Thanks Hans 👍
Hello, can I know what is the software or app you were using for this you tube? Thank you so much for I am a beginner to use a software or app to design and draw a garage project.
Hi Robin, my question is regarding an eaves detail for a tied roof. Is it OK if the connection between the joist/tie and the rafter is located outside the external walls in the eaves. i.e. the joist sits on the wall plate and extends outside the external leaf of the cavity wall by approximately 350mm at which point the rafter is bolted to It. The joints are strapped down to walls. Is this an acceptable connection. Also, Is it OK if the soffit is at the same level as the top of the wallplate which would be located on the internal leaf. The gap between the soffit and the outer leaf of the wall woukd then be bricked up. Would this be OK from a moisture penetration and insulation point of view? Most details show wallplate on inner leaf, one block above the outer leaf and soffit.
Nicely explained, what is the ridge to A frame connection detail like if the ridge beam is a lot larger section than the frame, would you beef up the frame to accommodate or is there a particular solution, say connecting a 205 uc to a 90x90 shs?
As long as you have a weld long enough, it doesn't really matter how small the box section is. If you need a longer weld (unlikely) you could put a haunch in at the apex.
Depending on the length of the ridge, properly built gable ends and a beam style ridge illuminates the need for steel
I agree, Jack. The ridge needs to be designed as a beam, whether timber or steel 👍
Fantastic information as always Robin! 👏🏻👏🏻 Do you do the structural drawings for this type of frame and steels? or do you have contact information for a company that does? I’ve just had plans passed for something very similar and need the structural drawings to send to the steel supplier for fabrication.
Hi John. Your structural engineer should be able to let you know about someone local, as it might involve coming to your property to measure up. Another avenue would be to contact some of the steel fabricators in your area as often they have their own draughts-people.
Great video
What software is this?
Hi Robin, another great video, thx.
I have a question regarding putting PV panels on flat roof by using proprietary mounting systems that do not penetrate the waterproofing layer and I wonder if you can teach us on how to assess
a. Wind uplift force and the counter weight required
b. Counterweight limit vs flat roof design load
Thx
That would be quite complicated and not easy to teach without any prior knowledge. Are you an installer or are you just doing this on your own property?
@@RobindeJongh thx. I am a homeowner and I have trouble to locate a reliable source of information to inform homeowner the consideration and risks of such installation.
Tiled roof PV seems more standard in the domestic world
I didn't understand in the other video, but this makes more sense. Why can't you just use a much larger chunk of wood instead of steel?
Hi Billy. Yes you could use bigger section size of timber, but that would be more expensive once you get above a certain size of lumber.
could this be done without the flanges on the I-BEAM? For instance make a flitch plate from like 3/4" x 7.5" plate steel? THen it would be less heavy and the flanges aren't really necessary, right?
Another great video Robin :-)
Andy B
Thank you so much for the video Robin. If you use timber A-frame instead of steel, how would you connect the ridge? Would fishplates be adequate in your opinion?
You could never get a timber frame to work as it's not possible to get moment resisting connections in timber, unless you use large steel custom made connections.
Thank you for making this video, it answered a lot of questions I had. I might've missed it, but what software are you using to demonstrate? I feel like it'd help me a lot with visualization
Hi. The software is geni.us/sketchup
it's not the slope itself that creates the force along the rafter, describing that way is not correct. It's produced by the sum of the reactions on the rafter (as all loads are vertical in your example)
The situation is that more of the roof is inside the support than outside it, thereby creating a moment in the rafter around the wall plate.
The moment applies to the ridge connection which can only produce a horizontal reaction, to resist the horizontal component of the diagonal force. The remainder of the resultant force goes along the rafter to push on the wall plate.
The steel beam adds a vertical reaction at the ridge connection, to resist the moment completely, meaning the beam cannot rotate via its moment therefore no horizontal reaction is present, as long as it's correctly birdsmouthed, the rafter would just sit there under dead load in the same way as any flat roof joist. If the rafters were not birdsmouthed correctly at both ends, then the rafters would indeed try to "slide down" and the connection would indeed be important. Failing to birdsmouth at the bottom only would in fact cause the wall to fall inwards, rather than spread.
The reason they would need to be tied together at the ridge via collar ties or strapping would be the wind load, shrinkage, movement, etc.
Hi Robin what is the software you are using
Hi Robin, great video. You mention in the video that the piers (either side of the door frame) need to be "665mm or there abouts" and from what I gather this is to do with lateral wind loading? Can you clarify this? I am doing something very similar (without moment frame) and at the moment my patio door is only approx 400 mm from outside face of perpendicular wall. Thanks.
Hi Sam.
The masonry piers need to be sized according to building regulations, approved document part a.
@@RobindeJongh Cheers Robin, think I've found the section I need.
I’m doing a vaulted roof similar to the one in your video, can you please tell me what size depth RSJ I should use to gain this effect on a 5.6 m wide by 6.7m long with the RSJ running the length of the building
Hi John. Try the free video here ua-cam.com/video/MVjuZEG-bP4/v-deo.html or for in depth training, my steel beam course: structural.thinkific.com/courses/steel-beam-calculations
What if it's a clerestory type roof with exposed beams? How do you place the beam?
Hi Robin good video, can I ask if I’ve followed this correctly you are saying don’t put a timber ridge in when there’s the RSJ at the ridge ? I can see the commons are notched around the RSJ’s flange but wasn’t sure if you meant that the commons simply meet at the apex and are nailed together or that there is a ridge to use as a straight edge or that there’s a gap ?
Kind regards
Hi Craig. You can still put a ridge board in to nail the commons to. Basically I'm saying that you need a structural ridge beam if you're making a fully vaulted roof.
@@RobindeJongh brilliant I would bob one in as that improves the build-ability as joiners like something to fix the plumb cut to. Thanks for the video 👍
Hi. Brilliant videos! I have a small garage, 7.86m Long by 3.63m wide (internally). Would like to put in scissors type car lift. A change to a vaulted roof would gives some more room. I'd like to put in an I beam to double as a "track" for a 500kg hoist
Any suggestions greatly apprecisted. Mat.
HI Mat. I can suggest my beam calculation course here: structural.thinkific.com/courses/steel-beam-calculations
What software are you using for this illustration?
Hey
if you do have the ceiling tie it is still a mechanism,because wind on the roof will exert horizontal load and you have three hinges, as you said the wall can't take horizontal load and be support to the roof as a cantilever. so how does it work ?
Three sides of a triangle is totally stable!
@@RobindeJongh Yes but the Tringale is sitting on two roller support, instead of one roller support and one pin support. I am structural engineer and ive never worked with masonry so am really interested about it.
And another question- do you have any recommendation on masonry books That are related to the structure stability(sorry about the bad English)
Hi robin what is the best safe way way to remove the old houses perlin . Which are 2 on 1 side 2 are other side and 1 joist or raftar in the middle . So they will be supported by metal beam each side about 600mm from the wall and 1 beam in the top middle . And its a loft conversion. Waiting for your reply. Thanks in advance
Hi. You can get the calculations done here: geni.us/loftsurvey
Great, informative, and well explained. The 3D models would be great to have. What CAD software do you use?
Hi Howard. It's geni.us/sketchup
Thanks for the answer. I would love to learn sketchup.
On the engineering front, the only thing I'd add is the practicality in terms of transportation of a fully wwlded frame. If that's not an option, then I tend to check what UC's would I need instead with flush front end plate splice connections at the points of counterflexure. Only sayjng UC's as they are better in torsion and buckling than the UB's.
Hi Ben - great observations as always! Yes, in many cases you would need a splice somewhere in the frame, and using a UC section would definitely make that easier. However, you would be increasing your section size greatly, which is a trade off. A box section frame can still be spliced, and if done at the apex it can be quite a neat connection.
@@RobindeJongh true. Swings and roundabouts 😉 Kudos for the million views. I can see these videos bridging the construction and engineering and giving builders an insight in the design process.
That would be use full 😎
Moisture in the wood may cause the steel to oxidize over time. If you treat the contact areas, it should prevent this.
I think or would prefer the additional steel A frame in the center location of the building roof structure. Now it would have the two steel A frames in that roof layout example. I guess you would argue that the cost would be driven up due to redundancy. Sorry I over kill it on engineering.
🚀Get my timber roof span tables: www.subscribepage.com/timber-reference
What sort of decking? Wouldn't it need to be an insulating decking?
This is often screwed up by carpenters, especially in garages (all in usa). our. Garage was retrofitted with a large beam to halt the roofcollapse.
Period Properties used to have Tie Rods with threaded ends from the outside walls with Plates to overcome wall spread due to downward forces pushing external walls out. In Cathedral Roofs these Tie Rods were exposed and accepted.
I note that in your R.S.J. comments you do not mention R.S.J. overhang Support requirements related to Beam Deflection, as a Period Property Restorer from way back, I would NEVER rely on an external wall for R.S.J. support, as an integral part of the resting walls I would demand a Support pillar/pier be built interlocking with the Wall Brick/Block work, Also the piers would be built of Engineering compression quality Bricks/Blocks on deeper stressed foundations.
Aesthetics come a distant second to Safe Practices... If the Client did not want a pier protruding then add a stud work Partition wall to cover the Pier
Do you have information on how the condensation is handled on a roof of this type?
Hi. You can go with a "warm roof" or "cold roof", and each handles it differently. Basically there needs to be an air gap for air flow to take the moisture away.
Thanks Robin. What software are you using for your demonstration?
Hi Sam. It is geni.us/sketchup
4:02 For adding supports
I have a roof of garage with cross beams suporting the roof which may roof space unusable. I would like to convert it in to a vaulted roof, it it possible?
How do I get in touch to get help on this specific matter?
By the way, I am not a builder and I am a woman!