Tying in Gable panel

[junglejim]

I don’t know that this needs anything extra but it was recommended by the supplier as we’re in a windy location. I’m just looking for advice on how to tie in. I’m going to take out the small brackets that were temporarily put in as will interfere with the osb but looking for suggestions of how to strap the gable into the roof structure effectively and without interfering with anything.

 Thanks

[joe90]

I would ask the supplier exactly what “tying in” they recommend (I am not sure what they are trying to achieve).

[ProDave]

Surely a proper drawing exists somewhere detailing the fixings to be used?  None of those look adequate or anything like as substantial as the brackets used on ours, and specified on all the drawings.

 

The fixings of the rafters to the Glulam look inadequate to me as well as the brackets fixing the glulam to the gable.

[saveasteading]

1 hour ago, junglejim said:

how to strap the gable into the roof structure

It needs long straps by Simpson or equal.  These.

And lots of them tying the roof down to the walls. Not that the wall looks very strong either, so the ties must go down to the cross beam/ lintel and then that needs fixing down at the ends.

Someone should have specified them by type, location and fixings. Worrying that nobody seems to have done so.

Wind uplift forces are scarily high and you genuinely could lose that roof.

Do Not take any brackets off.

 

[junglejim]

1 hour ago, saveasteading said:

It needs long straps by Simpson or equal.  These.

And lots of them tying the roof down to the walls. Not that the wall looks very strong either, so the ties must go down to the cross beam/ lintel and then that needs fixing down at the ends.

Someone should have specified them by type, location and fixings. Worrying that nobody seems to have done so.

Wind uplift forces are scarily high and you genuinely could lose that roof.

Do Not take any brackets off.

 

Thanks. Going to go back to the manufacturer & installer to see what they say but keen to strap up. If still got temporary timber ties in place so not worried about it going anywhere yet. The ridge glulam is going to be exposed so can’t strap along there where it will be exposed . I can go onto the horizontal glulam. Would welcome any advice. 
Thank you

[ProDave]

1 hour ago, junglejim said:

Thanks. Going to go back to the manufacturer & installer to see what they say but keen to strap up

It is the designer that should specify it, not the glulam manufacturer, they just make what is specified on the drawing.  Likewise the installers (should) do what the drawings instruct them to do.

[junglejim]

12 hours ago, ProDave said:

It is the designer that should specify it, not the glulam manufacturer, they just make what is specified on the drawing.  Likewise the installers (should) do what the drawings instruct them to do.

Thanks yes will go back to the designer. Looking back at the designs I can’t see any straps specified. I’m wondering if it’s because the panel above the window is so small that it doesn’t need much and is has a structural pocket so the ridge glulam is essentially holding it together… I’d prefer something else though! The main structure is below the window and tied into the side walls and floor so not an issue. 
 

Any further advice welcome.

Edited 9 hours ago by junglejim

[saveasteading]

Can you give us a sense of scale? It may be a very heavy construction with a huge glulam and oversized rafters.

[junglejim]

1 hour ago, saveasteading said:

Can you give us a sense of scale? It may be a very heavy construction with a huge glulam and oversized rafters.

 

[junglejim]

1 hour ago, saveasteading said:

Can you give us a sense of scale? It may be a very heavy construction with a huge glulam and oversized rafters.

Shared some dimensions. Yes I think it’s been designed with heavier and more timbers than necessary.

[JohnMo]

You should have structural drawings from roof supplier or approved ones by your structural engineer. If you have neither get them done ASHP.

 

Nothing so far mentioned wind loading, roof overhang etc

[junglejim]

12 minutes ago, JohnMo said:

You should have structural drawings from roof supplier or approved ones by your structural engineer. If you have neither get them done ASHP.

 

Nothing so far mentioned wind loading, roof overhang etc

Thanks yes have structural drawings but can’t see anything specifying ties to be used. I will go back to the designer though to see as originally this work was to be carried out and overseen by the TF company so there may be more that I don’t have.

[joe90]

23 minutes ago, junglejim said:

Thanks yes have structural drawings but can’t see anything specifying ties to be used.

Not good enough IMO.

20 hours ago, saveasteading said:

It needs long straps by Simpson or equal.  These.

Yes these are standard practice (I missed this earlier, glad @saveasteading is awake) at least it’s not too late to fit them. Instead of those little rafter brackets I would strap rafter to rafter on the outside over the top of the glulam with banding.

 

[junglejim]

16 minutes ago, joe90 said:

Not good enough IMO.

Yes these are standard practice (I missed this earlier, glad @saveasteading is awake) at least it’s not too late to fit them. Instead of those little rafter brackets I would strap rafter to rafter on the outside over the top of the glulam with banding.

 

Thanks. Am I correct in understanding that this would be to strap the rafters together… I think the engineer recommended the rafter brackets at the top. They’re also mechanically fixed with nails at the rafter ends and osb sheathing presumably gives additional strength etc. If straps are needed too at least that’s fairly easy at this stage.

 

My concern was more the gable ends and what is needed. I’ve emailed the designer and engineer for advice but would welcome any thoughts on here.

 

 Thank you

[joe90]

22 minutes ago, junglejim said:

Am I correct in understanding that this would be to strap the rafters together…

Yes,  if it were me I would use 600mm strap (300mm down each side on every rafter

yes nails in rafter ends into each other and/or glulam.

regarding the straps i would put one vertically strapping the glulam down the wall and even into that lintel. Another two each down the wall just outside the lintel area. You have not mentioned the wall plate at the eaves but these too should have wall straps.

 

note, I am not a SE but have done many  jobs like this in the past.

 

just found this……

 

Building regulations require restraint straps to be used in certain situations, including: 

 

• Spacing: Restraint straps should be no more than 2 meters apart for dwellings up to 3 stories, and no more than 1.25 meters apart for dwellings over 3 stories. 
   
• Location: Restraint straps should be provided on one side of the wall, unless the design requires strapping on both sides. 
   
• Attachment: Restraint straps should be fixed across at least three ceiling joists. 
   
• Length: Vertical strapping should be at least 1 meter long. 
   
• Wall plates: Holding-down straps should be at least 1 meter long with a cross section of 30mm x 2.5mm. They should be spaced at a maximum of 2 meter centers. 

[junglejim]

13 minutes ago, joe90 said:

Yes,  if it were me I would use 600mm strap (300mm down each side on every rafter

yes nails in rafter ends into each other and/or glulam.

regarding the straps i would put one vertically strapping the glulam down the wall and even into that lintel. Another two each down the wall just outside the lintel area. You have not mentioned the wall plate at the eaves but these too should have wall straps.

 

note, I am not a SE but have done many  jobs like this in the past.

 

just found this……

 

 

Building regulations require restraint straps to be used in certain situations, including: 

 

• Spacing: Restraint straps should be no more than 2 meters apart for dwellings up to 3 stories, and no more than 1.25 meters apart for dwellings over 3 stories. 
   
• Location: Restraint straps should be provided on one side of the wall, unless the design requires strapping on both sides. 
   
• Attachment: Restraint straps should be fixed across at least three ceiling joists. 
   
• Length: Vertical strapping should be at least 1 meter long. 
   
• Wall plates: Holding-down straps should be at least 1 meter long with a cross section of 30mm x 2.5mm. They should be spaced at a maximum of 2 meter centers. 

Thank you that’s all useful.

 Bit of a can of worms… trusting that the TF company installed the frame as needed and BC haven’t said anything so may be worrying unnecessarily but… the wall plates are basically anchored with bolts into the slab through the sole plate. I can’t see any straps… is that necessary. (Note no block work just Timber frame on raft slab.

[joe90]

7 minutes ago, junglejim said:

BC haven’t said anything so may be worrying unnecessarily

Maybe but best to check as you have done. Ah didn’t realise it was timber frame (note to self “don’t make assumptions”) 

on the other hand over engineering cant do any harm (I tend to over engineer but gives me piece of mind). 

[joe90]

11 minutes ago, junglejim said:

the wall plates are basically anchored with bolts into the slab through the sole plate. I can’t see any straps…

The wall plates I was referring too would be at eaves height which you don’t have (again on Blockwork which you don’t have,!!)

[saveasteading]

14 minutes ago, junglejim said:

 BC haven’t said anything 

They are having an overview in limited time, and will often miss something. They are not your quality control manager. Also they may assume that eg ties  are still to be fixed. 

First impressions of your building are good  and that may give false assurance that everything is done properly. 

[joe90]

As you said above, check with the supplier what should be there and add stuff if it makes you feel more comfortable. I have never built timber frame so strapping may be not necessary.

[saveasteading]

2 minutes ago, joe90 said:

so strapping may be not necessary.

Any roof will lift off if not fixed one way of another. Straps aren't needed on a steel portal frame for example.

But most houses are walls with a roof laid on top, and need tying, and straps spread the load nicely down the wall into timber or masonry.

[joe90]

18 minutes ago, saveasteading said:

Any roof will lift off if not fixed one way of another.

I would agree but not having built in timber frame I don’t know how timber walls and roof are connected which is why I suggested contacting the supplier for confirmation of their requirements. 

[junglejim]

57 minutes ago, joe90 said:

I would agree but not having built in timber frame I don’t know how timber walls and roof are connected which is why I suggested contacting the supplier for confirmation of their requirements. 

Thanks @joe90 good advice. Probably worrying about nothing as on closer inspection looks like the roof ladder is screwed into gable and rafters ends are nailed together but would rather air on the side of caution and double/triple check before closing it all up 👍

Edited 1 hour ago by junglejim