Thats a great insight and personal view, im sure will be helpful for many people (like myself) deciding from this system to the mote traditional way. Top work!

I've absolutely no interest in doing a loft conversion, yet I found myself mesmerised by this video!

Thanks for the great insight from an engineer's perspective. I am considering a loft, have seen Rob's videos and I find proper measurement and pre-manufacture appealing. Will be on my shortlist.

I love watching the ecotrus lads work, so this is very interesting. Thanks.

It's very generous of you to post this video, very helpful.

This is a generous gift to all of us KZfaq information seekers Robin. As a tradesman my past education is limited so to listen and view your knowledge is very much appreciated. Thank you

Excellent and very helpful as I consider this approach for my loft conversion (60 yrs I failed my bending moments course). Like to understand this in a conventional 1960s purlin roof

Hi Robin, great detailed review, nice to get a professional opinion from someone with knowledge and experience in this type of thing. I'm a carpenter myself and I'm wanting to open up the space in top of my double garage, I think the steel construction would be the easiest way to go but from a price point it would be expensive as I would do the labour myself if I went down the traditional route 👍

Fantastic explanation of this system. I am considering this system for my loft.

Hey Robin. My roofing contractor put me on to EcoTruss. I [was] a civil-structural engineer and had just put together an outline for a dog-kennel dormer to go into our bungalow hip roof, but it needs to be done without disturbing the upstairs en-suite shower room. I had dreamed up a structural framework to allow this "all by myself", and now discover that Eco Truss have done it already! My vision was of hot-rolled sections bolted together, but this is of course far better - and lighter. I also like the idea of pre-formed holes, which in our case can be used to re-route existing drainage pipes. I note your warning about 'cold bridging' - will need to check our contractor sorts this out in design/construction. Absolutely brilliant video. Thanks.

Another great video! Could you do a video showing the calculations that would be needed for this system? Particularly the Dormer version as it looses the triangulation. Would be very interesting!

Just having mine finished tomorrow solid system all locked together ( boys work hard ) 👍

Funny just asked Rob how do you get the strengh then this popped up thanks great video

Interesting informative surveyor/engineer view. Actual jobs shown very fast with Rob & gang doing the job experts fit fast skillful good teamwork, sheer speed very persausive. I like the traditional framed roof with dormer one side roof windows the other. On old roofs while converting best recover with lighweight solution insulating the same time. Installing solar panels on duff roofs bit silly. I have a cornish unit awkward roof not well constructed would like to convert hip to gable if practical for extra space 20' internal x 14' between current purlin lines likely get 18' + width decent ensuite room/attic pad with fantastic views! Staircase installation space/access looks very difficult anyone done one? Advice gratefully received!

Thanks a lot for taking time to share your views. I’m still 50/50 on timber or c section at the moment

Really interesting stuff!

I am really enjoying this series. Can you cover how converting from a hip roof to Gable style roof?

Perfect! I just stumbled on the Build it with Rob channel and saw this Ecotruss system. This looks like it will work well with a dormer that im planning for my Loft conversion. Brilliant stuff!

Thanks for your very instructive videos Robin - especially, for me, that on "ecotrus" loft conversion. There might be quite a number of folk who would be interested in a similar analysis of the "telebeam" option in which 3-part telescopic aluminium bearers are slid in at right angle to the eaves. That too uses metal beams alongside the horizontal joists but excludes them from the pitched rafters - presumably relying on horizontal timber collars at ceiling height to provide support for the upper roof. It strikes me, as an amateur, that this might avoid both the additional cost and weight required to be borne by lower levels and also thermal bridging of metal under adjacent to roof tiles. Although such bridging at eaves and the installation and maintenance of services through metal box and I-sections are questions in my mind.

Great video Robin. One thing to consider for any loft conversion is the supporting walls. For Ecotruss solution some of the floor C sections may be above window lintels so extra load added which could be bad. For loft conversion with steels between the gables (new loft joists on hangers) that will put extra load on the gables. If made of blockwork are 3.5kN blocks acceptable at 1st floor level, and how much will padstones help. So another video on the supporting walls would be good. E.g. do BCO need all lintels exposing i.e. dry lining removing, also do the building foundations need exposing? Thanks again.

Hi Robin. Like this video very much. Can you make another video to explain the durabase modular extension base system and compare with traditional construction? Thank you

Great analysis, thanks :-)

Very useful informative explanation Would appreciate similar xplanation on dormer roof . As we carry out traditional loft builds Few of our clients prefer not to have eve space , you loose from at least front section approx 2/3 mtres of usefull floor space . So we use rafters 175 mm & strap & bolt in. Im assuming to do that with sheet metal £ would not be possible unless you use steel beams.

Thanks for the advice.

Very informative...thanks.

Good job, when they walk on the steel floor sections they do seem a bit flexible actually. If I was looking to do this then I would try to reduce the floor section depth to get more head height. I do realise the bending strength/stiffness comes from the depth Ixx however. Maybe look to maximise this shape. It looks like the holes are also for weight reduction as the material in the middle is doing next to nothing. Not sure I like the self tapping screws they use when the steel is so thin. Thanks for the review.

One of the benefits I see is that the reinforcement is slid in front to rear, so doesn't require side access through gable ends or into party wall. Especially a benefit for a mid-terrace house. You mention cost as a negative, but on their website you can enter your dimensions for an instant estimate and it's actually quite cheap. I imagine the reduced on-site time is the benefit. Less man hours. Try it yourself. Finally, one negative that unfortunately makes it incompatible with my house. It has to sit on the external brick walls. My house has a low roof, so the soffets are lower than the ceilings. You can effectively see the inside of some of the roof on all the external walls. So when I enquired about it, they said it couldn't be done.

I have been considering a system like this since my home as a load bearing spine wall parallel to the loft joists. Just over 30% of the spine wall is built from the ground right up to the loft, the rest is sat 400mm in on 1st floor joists so I don't think I can put a UB or any extra weight to split the floor in the loft otherwise it could cause cracking to ceiling.

The ends cuts are im assuming sprayed with cold galv it’s common in manufacturing steel products, like your vids you do go in good depth

This is basically a flitch technique with lighter cold rolled sections. The timber sandwiched at the wall plate provides the rigidity for the joist ends and the c-section on the rafters prevents deflection. Also the rock wool insulation laid within the joists would prevent cold bridging as it’s pushed to the end?

Hi Robin. Thanks for the detailed explanation on the workings of eco truss. Nothing I can’t wrap my head around is that how does their dormer version work without a ridge beam. Please shed light on how structural strength is achieved with half the roof replaced with flat dormer that too without a ridge beam Thanks

Great video , been looking at Robs videos also. Do you have any videos on lifting beams and spreader beam for the lifting industry?

6:30 I’d say they are load bearing. Any truss would drop even with the extra steels. I’ve build steel houses in NZ. That gauge and type of steel is flexible. Thing I’ve noticed in the video of builders using this system is they never vacuum up the drilling shards. This is the start of those steels rusting. Clean up before covering over. And spray any drilled or newly cut areas with zinc rust proofer.

Excellent analysis and overview by an engineer. Your independent assessment is greater value than to get to know the system by working with Eco Trus closely, as you'd become a sales agent for them. What about putting solar panels on the new roofs? Can they handle the added loading? What about solar water heaters which are substantially heavier? What about adding substantial hot water storage inside the new room to use as energy dump when electricity from solar panels not needed?

This is so helpful Robin. I wonder how this system performs when we have a dormer roof.

Well done jop how much like this loft convention

I love experts....

Interesting video

Hi , In the videos they do say that all habitable loft conversions ,that it is to building regs . I have spent 50 years in the construction industry and I think the system and the ease of building and the inconvenience to the living part of the property is first class . Even if timber is cheaper ,there is a lot more labour hours on site on site , so it is horses for courses .NO crane needed and no heavy steel work and very little scaffold hire .

The stud walls add strength, the cut out holes have the rafters that continues to the end bolted more than once, the transat at the ridge will hold. No bounce on the floor as the floor panels are the strengthening skin. The thermic barrier can be maintained with insulation. Because you remove the rive tiles for access you can insulate easily.

Mine is getting fitted next week. The amount of extra room (length and height) I’m getting from this system compared to the “traditional way” is unbelievable.

HI, in the Pro box you can add less cost with skips: with the cold rolled prefabricated steel joists there are no off cuts that need to be discarded at aprox 500£ per skip

Would you recommend ecotrus over traditional methods? I'm not too fussed about price if the end product is of a higher quality.

How are you making a structural connection between the steel joist and steel sister rafter?

Hi Rob, Another company I was looking at for a loft floor is called Telebeam. The beams are telescopic so can be adjusted if needed. I don't know if you are aware of them but I would interested in your thoughts if you do a video on that product as well

Does this work on a timber frame house?

A lot of their videos seem to be creating additional usable space, and not extra 'rooms' as such. I've seen one or two that are full habitable loft conversions. I think the mention of 'bolts' is interesting as I think it's all done with TEK screws, so it's more open to the DIY/jobbing builder market. The air gap below the felt should be 50mm (assuming it's using the original [non-breathable] felt). Planning permission should also be in your mind when you're looking at converting these loft spaces. You will need planning permission once it is above a certain (volumetric) size. There are other systems like 'Telebeam' too that are worth looking into.

Hi Robin Thanks, very informative video. Do you think the cold bridging would be an issue, if the insulation is “tucked in well” with ventilation provision would minimise the issue and any condensation. Thanks

Interesting system, trusses are at 600mm centre's. I've done loads of loft conversions, always been 150mm x 47mm rafters and 254 or 303 steel , spliced twice, nightmare to physically get it into the lofts, although mansard roofs are much easier, looks like an easy system to use on new builds with trada trusses,

So essentially the steel C section beams are doubling up each original timber triangular truss. Could the same result be obtained by using , say, laminated OSB cut into lengths and bolted through both sides ?

another option worth talking about if possible? Ply box type of conversion using hangers off the box, party wall agreement may be needed as with gable to gable steels

Hi would you consider this as a non-standard construction and would cause any insurance or future sales issue? In addition, if the rear wall is to be opened up on the ground for a single-storey rear extension, what would be the implication compared with a traditional loft conversion (in which side walls are used for supporting the loft)?

Gussets at the top

One last point, a normal truss roof (assuming no sarking boards) will have longitudinal and diagonal bracing, and restraint strapping into the gable at rafter and possibly also ceiling level for tall gables. For the former Ecoloft will remove, and is the diagonal element provided by the plasterboard? Stud ladders would also help a bit if securely fixed. For restraint strapping not clear yet how Ecotruss cut and fix to the new steels. Any helpful thoughts? . . . and what would you guess BCO would want to see for these aspects. Final thought is ridge ventilation prob had to be added to comply with latest standards? also what about vent at top of the new eaves spaces?

Seems to me that a simple triangle shaped flat steel gusset at each end and the peak would provide adequate strength and eliminate the need to cut off that bit they are currently.

great video rob, but all the weight of the steelwork, would it effect the integrity of the house foundations?

Great explanation. Could you do a similar video showing Telebeams? It seems a much simpler solution. Aside from the weight and handling it I can’t see why you couldn’t use timber in the same way as the telebeam solution for limited spans especially seeing as the cost £450 each!

4:50 That hole actually increases the strength because it's pressed out and has a lip all around it. You'll find the same thing in aircraft bulkheads

I'm having a new loft conversion this year which will involve the old roof and new roof space of a new extension. I'm still wondering about using ecoTruss for the enture roof structure but can't make my mind up. There is speed of construction as you said but there is also cost. And you have now highlighted some other issues, I wonder if ecoTruss can respond to these issues. I think the idea is good. I also wonder if their design does come with full approved design calculations that Building inspector will accept. Still watching this space 👍

In this you say its only the centre section of the floor that gets strengthened joists in a traditional conversion? But that must mean the rafters need to be much more strengthened than with the eco truss? I know the structure works together but you can’t just have a strong floor as an island in the middle of the span? Something has to actually bridge the load out to the walls? ....watched your other videos and it all makes sense now

Great video! I was wondering if you've seen a Telebeam system - a similar technique to Eco trus but aluminium is used instead. The ends are telescopic (so no need to get it manufactured to measure) and it does not requires the upper chord. Looks much weaker than this - but I was wondering if it is?

We are wanting to turn our trus loft into a room for our son and not sure what route to take and which would be most cost effective especially in the current covid climate. Would be interesting to get your views on way forward for a loft conversion?

I’m curious as to how they deal with the various cold bridging issues that this creates.

Hello what design program are you using

Looking some of the newer videos they have done, the hole you mention has been moved back and there is a bolt hole for it to stop rusting :) Interesting video as this is something I’m looking at

I like the ecotruss systemic . Robs makes it look very stress free for the owners. Our loft is a bit tight for a conversion , I was hoping this system would yield a larger overall internal loft height ?

Does anyone know the max length ecotrus will go too ?

Hi Robin. Being in the sheet metal trade I would think that the frames would all be cut/mitred before being galvanized

I don’t even own a house but still watched

Is there a similar system in the United States available?

i did get a quote for ecotrus. They don't laser scan anymore,that's disappointing as possibly one of the time saving contributions. Stairs are extra, as are window openings, also the price is not for a weather proof structure externally. The waiting list is months. I was really keen however I am now considering conventional build as I can save 50% on the quote provided. More if I do some of the work myself.

How do you run your plumbing pipework and power cables through these steel joists? I'm assuming you can't cut a hole through like you can with timber?

Have you a rough idea of the span limit using ecotruss also would a benefit of these truss mean potentially a thinner floor is possible?

If the circular holes are positioned properly that end joint could be positioned in such a way as to avoid the circular holes. The steel floor joists or beams it seems to me could be installed in two parts along their length and joined in the centre with a fish plate. This could be then done by the average competent person without removing any tile sections. Having owned home (our first home in Aust) which was an all steel frame construction, I cannot see the necessity of creating i beams sandwiching the ceiling joist ... certainly the construction of our home used only C beams as floor joists and ceiling joists. The proper fixing of sheet flooring would avoid any flexing of the beams once installed. The end sections could be sprayed with a little polyurethane foam on the ends... I like the idea of truncating the steel before the edges of the roof to avoid cold bridging... Buying commercial 150 mm (or 200mm) x 50mm C section without the holes would be easy enough.... there are enough tools available to cut circular holes of appropriate size where needed on site rather than in a factory.... further cost savings could be achieved in this way. The galv framed house we bought (new) in the late 70s is still standing as fresh looking as ever...and hey...in South Aust remains termite free. The only downside was floor bounce (like most Aust homes it was single storey). The house was essentially constructed like a ship and designed to flex in the floors...it was supported only by perimeter foundations played havoc with my hi-fi turntable... We insisted the builders came back and put appropriate concrete slab plates on the ground underneath the floor and their own proprietory floor jacks (which were part of the system) at appropriate places under the house. That same construction system utilising footings and floor done in a single pour (as is common in many Aust homes) and helicoptered off to make the house floor smooth and flat would perfect the system. All intrernal and external walls and ceiling were insulated with rockwool (I think that was a heated ans spun form of gypsum... could be totally wrong...it was not asbestos I know that). I don't know why perimeter foundations with concrete infill beams are used in Britain... Footings dug, appropriate continuous (taped) membrane laid in all trenches and across floor space with polystyrene waffle pods places to cut down the volume of concrete and insulate... with rebar in footings and reinforcing mesh across the floor area could be used....and seems to me to make sense.

you mention that the stud wall frames were likely not supporting the rafters, i was wondering why there seemed to be no fastening between the wall and the rafters but it makes sense if they’re not taking load. If it was all timber would you expect the stud wall to provide support for the rafters?

With your knowledge do you think this works on a new style build that is a timber frame with no work needed to strengthen the house?

Does it not gain headroom when compared to I beams over the top of the existing lower wooden beam.

The foundations of the house have not been designed to carry the self weight of the additional steel or the imposed load from the loft conversion , so how do you deal with this?

What happened to the original fink roof binders? They would clash with the cold rolled channels.

Just another point on services and specifically electrics. Most lofts have cables for 1st floor lighting, fans etc here there and everywhere possibly routed as the crow flies and over trusses. Assume with Ecotruss it would be better before fitting trusses to rewire and run all cables off to the eaves, and connect there using cage clamp terminal JB to a highway running through the Ecotruss service holes (hole edges protected with push on plastic edging) i.e. no junction boxes under the new loft floor. Only thought on plumbing, keep it on the opposite side if possible. My only electric worry then is how to insulate from any damp/condensation at the eaves. I think Ecotruss do normally board the eaves space.

I don't recall seeing any longitudinal bracing, when I've fitted timber trussed rafters for compliance there's been timber everywhere. Can't imagine calcs for the BCO would be an issue, they'd come out of the computer that does the design just like for timber trusses, when they've been required and I've sent them in, I doubt the computer calculations are checked on domestics, you just know it's big enough from experience.

The truss mbrv duznt need to go to the end as it can be supported off the horizontal steel. No load on that triangle

I imagine the reason the hole is there at the end is something to do with keeping the costs down during the manufacturing process. ie The holes are continued across the entire truss, and the truss is just cut down to length when the dimensions of the loft are specified- so it can just be cut down to size to suit the application?

Your comment at 5m in about it being weak due to the hole, surely there is still a significant strength from the existing rafter structure, as these are still in place?

Seems over kill to me, should be enough to have 1 lightweight steel truss per joist ( could also be a seam welded full box section) and throughbolt the steel and joist , then retriangulate and reinforce the rafter structure in timber as normal. The method of inserting all the additional reinforcing through lifted sections of roof can be applied to any method of reinforcement/construction. You'll definitely get a lot of condensation forming on the cold ends in the eaves and it will keep the loft floor colder than it would be unless the eave space is fully insulated.

How would you build the loft and how many steel you would have used ?

Wow that is a lot of steel work being inroduced

I do not rate the Eco Truss videos very highly as although the product is good they skip over some important bits eg fastening the steel to the wood, and the cost of each beam I never heard mentioned. Also, you have the extra cost of scaffolding and crane or a team of men to lift the heavy beams. Then there is putting the lower removed roof tiles back on which is harder with an old roof - tiles crack etc. With wood you can cut it more easily eg if there is a pipe or something to go over or you need a hole cutting - wood is easier to cut/modify than steel - easier to work with. It is hard to get measurements spot on - with wood this error is less likely as you can cut on the spot, & even extend a piece a few inches. I think their steel system is for the 50k + projects. I like it though.

I think the hole is to deduct the weight

Does this roof need purlins just to take any bowing

Is there a need to get your own architect drawings first ?

You missed out the fact that the bottom of the 'steels' are fifty millimetres above the bottom of the truss cord.

But..have they checked the torsion?

Actually how this works is its bolted at many points in between, this makes it important for the bottom beam to bend, secondly the beam is still carrying most of floors weight at the ends the u beam is just there for it not to bend so the holes dont matter

Why the holes in the section?

Hi great video. I was wondering if you would be prepared to send me this drawing file via email?

I assume this product cannot be used on a normal cut roof i.e. rafters sat on wall plate then joists which run across (not a truss roof)?

it's a steel truss...what's "eco" got to do with it?

Flat roof, never a good idea.