Roof construction for a small hall

[Talltim]

I'm building a model of the Primitive Methodist chapel that was in Arkwright Town before it (the town!) was demolished. I'd like to added some bracing under the roof, mainly to strengthen it and keep it from sagging, but it also needs to be rough visually right (not sure you'll be able to see it through the windows but I'll know its there!)

The trouble is Google doesn't seem to be my friend, I'm either finding things that are too old, too new, too fancy or too American. and I don't know the right terminology. What would the structure be like?

[Joseph_Pestell]

For a building of that size, I think that there would only be one roof truss, halfway along the building. Other than that, from the interior one would probably be able to see the two purlins and the central beam along the apex.

 

My brother-in-law lives in a barn conversion (a rather larger building) of this sort of construction. I can take a photo if you want.

[Talltim]

So so the truss would be basically a triangle? Would the horizontal be at the bottom of the triangle, i.e. at the top of the side wall? Also would it have a vertical on the centreline?

[Talltim]

Thinking something like

Two trusses because of the locations of the windows

Edited July 19, 2017 by Talltim

[Talltim]

or maybe

[tamperman36]

I would expect it to have had more trusses as they take the weight and stress of the entire roof, you'd be surprised by how much a roof full of tiles actually weighs. I would space trusses about 2-3 feet apart, in 4 mm scale that's 8-12 mm apart. You could use match sticks to make you trusses with little pieces of silver foil glued over the joints to represent the metal plates used on real roof trusses.

For more ideas and pictures try looking on Google Images and look at roof trusses.

[Talltim]

From Googling, modern buildings seem to have far more closely spaced trusses than older buildings

[chris p bacon]

Talltim, the couple of drawings you've done are representative of modern house roof construction. For a 'Victorian' chapel the roof is more likely to be a 'Hammerbeam' truss construction.

These were quite widespread as it meant the roof space was open and thereby the congregation were 'Closer to God'

 

Construction was the trusses spaced every 8-10 feet and carrying Purlins at 4-6' spacing with the rafters on top of these. The section size would have been 5"x6-8" and the Purlins 6"x4". Ceilings were generally boarded either above or below the Purlins.

 

Hope this helps.

Edited July 20, 2017 by chris p bacon

[Talltim]

Talltim, the couple of drawings you've done are representative of modern house roof construction. For a 'Victorian' chapel the roof is more likely to be a 'Hammerbeam' truss construction.

Hammerbeam .jpg

These were quite widespread as it meant the roof space was open and thereby the congregation were 'Closer to God'

 

Construction was the trusses spaced every 8-10 feet and carrying Purlins at 4-6' spacing with the rafters on top of these. The section size would have been 5"x6-8" and the Purlins 6"x4". Ceilings were generally boarded either above or below the Purlins.

 

Hope this helps.

Think I saw that image in my searching. I'd wondered about the level of fanciness required for what seems to be about as basic a church building as there is. Trouble is there seem to be few photos of the interiors of small non-conformist chapels, probably not as photogenic as more older or more ornate churches.

[phil_sutters]

For a simple design you could do worse than look at the interior shots of this old Welsh chapel.

http://map.coflein.gov.uk/index.php?action=do_details&numlink=6974

[Joseph_Pestell]

I think that you have it right with your drawing in #4. As you rightly note, there should ideally not be a truss over a window opening.

 

Primitive Methodist congregations were not usually wealthy folk. So I think that a simple truss, as per a similar-sized barn is definitely the order of the day. For comparison, my brother-in-laws barn (house) is about 20M long and has five trusses, so about 3.3M apart. Like your building, a slate roof so rather lighter than some tiles.

[tamperman36]

As has been mentioned the trusses used in older buildings are if you study pictures generally a bigger section of timber which would allow for larger spacings between them.

[chris p bacon]

I think that you have it right with your drawing in #4. As you rightly note, there should ideally not be a truss over a window opening.

 

Primitive Methodist congregations were not usually wealthy folk. So I think that a simple truss, as per a similar-sized barn is definitely the order of the day. For comparison, my brother-in-laws barn (house) is about 20M long and has five trusses, so about 3.3M apart. Like your building, a slate roof so rather lighter than some tiles.

 

The design of truss shown in 4 was seen but could actually be harder to erect on a large building/Hall.

 

Don't confuse the intricacy of the woodwork on the hammer beam  truss with its simplicity, the design meant it could be cut and assembled in place rather than hoisted up. It also used small lengths of timber whereas the king post needs large & long lengths which were far more costly.

[Talltim]

I think I'll go for a non-ornamental hammer beam truss. I was originally reluctant because of the extra work required, but I've realised I can solder up a brass section truss as similar to my second drawing and add cosmetic hammer beams.

I've found it difficult to research, I can either find older chapels with simple trusses or larger turn of the century chapels that are far more ornate.

Edited July 21, 2017 by Talltim

[Nearholmer]

Looking at the age of the building in question, it might have had trusses with tension members made from wrought-iron rods, with turnbuckles, and the rest in timber. My observation is that this composite construction was quite common in village halls, schools, and the like, where cost was presumably a major factor.

 

The one in the photo below is a bit fancy, but it illustrates this form of construction.

 

Another cheap truss was the 'scissors', all in timber, of fairly deep, but narrow, section, but I've got a feeling that was a late Victorian or Edwardian idea, and it turns up in things like army huts. The PD&SWJR had an overall roof of this form at its terminus, IIRC. ( yes, and this gent has built all the trusses to scale in 4mm http://www.rmweb.co.uk/community/index.php?/topic/65255-callington-branch/ ) Theory says that a scissors is an expensive truss, because it uses a lot of wood, but it is easy to make from planks, nuts, bolts and washers, with no skill needed in the joints.

 

If you google "village hall interior", and select "images", you get a massive variety of trusses to study at your leisure!

 

K

Edited July 21, 2017 by Nearholmer