DBT85s Workshop - Moved in and now time to fit it out

[DBT85]

.......Out of interest. Is a rafter tie needed for every pair or is it every other or every third or something?......

The roof has to be looked at as a whole. The stiffness of the wall plate and the strength of the ridge beam come into the equation, as do the existence or otherwise of purlins. The point it, you can generally have widely spaced ties, or no ties at all, if that's what is designed in from the start. My suggestion is to say what you would ideally end up with and let's work backwards from there.

Thanks Mike.

I'd really like as much open space above me as possible while also obviously having some storage up there. Right now the plan has a 195x67mm beam in there, rafters every 600/610mm to match the walls and I've also put ties in on every rafter for the sake of it with the top of each being 1/3 of the vertical height from the top of the top place to the top of the ridge. From the inner edges of each top plate the span is 6639mm. Again, I'm literally making things up so everything can and likely will change as required.

The roof will be Onduline or a metal tile like Decra or Metrotile.

Can you offer any suggestion on what mix the concrete should be. Gen 3, C25 or 30, RC30 etc? Since I'd be putting mesh in shuld I be thinking about an RC mix or not bother for this installation?

 

[DBT85]

My 2p having been down this road. In no particular order:

If I think of anything else I'll add it.

Thanks for the input Steve. Your own experience has taught many a potential builder some valuable lessons!

I'm praying all of my materials arrive in one standard or another. I've seen some builds where someone got 50 odd sheets of OSB delivered and half was metric and half was imperial from the same yard!

I paid £95 per m +VAT for C25; that was near London so prices may be less elsewhere.
To save on concrete I dug thickened edges to the subsoil (up to ~400mm deep) and then just had a 100-150mm main slab with mesh in it. I suspect because of clay heave you might want to have a thicker main slab though.
If you order volumentric concrete they will only mix as much as you need which definitely saved me money as my estimate was far off!
Good luck with your build,
Dom

Dom, was ther any particular reason you ended up with C25 rather than an RC mix or C30 or something?

As you say, I'd likely end up with a slab almost entirely 200-250mm thick due to the clay and proximity to trees.

Volumetric is something I've looked at, just not got any prices yet.

+1 as steve says for a water supply even just for an outside tap. as you will have a trench open anyway, bung in a bit of blue pipe.

As Mike says it's not quite as simple. For me to run the blue stuff (we have loads here kicking around) would be a lot more work as the supply is the exact opposite corner of the site. I'd have to lay a trench all the way around the house. I could run a cold supply in from the nearest bathroom with no real issue in some standard 15mm with a bit more ease.

Mike, can that not just go to the same (presumed) soakaway that the roof runoff is going to go to?

Roof runoff is an issue I've not yet really solved yet. I've not seen much detail in anyones builds about what they have done and being on a lot of clay a soakaway is possibly less useful. I don't know at what point one needs a soakaway. We have a huge dutch barn here where all the water just runs off the roof and onto the floor!

 

[MikeG.]

........I'd really like as much open space above me as possible while also obviously having some storage up there. Right now the plan has a 195x67mm beam in there, rafters every 600/610mm to match the walls and I've also put ties in on every rafter for the sake of it with the top of each being 1/3 of the vertical height from the top of the top place to the top of the ridge. From the inner edges of each top plate the span is 6639mm. Again, I'm literally making things up so everything can and likely will change as required

The span is 6.6m? Don't you mean the ridge length? The span is at 90 degrees from that. The distance between the walls that the rafters sit on.

You're getting confused as to the role of a ridge beam. It exists only as one way of preventing spreading (the pushing apart of the walls). It serves no other structural function. Therefore, if you have ties at every pair of rafters as you show in your drawing, then there is no need for a ridge beam. Indeed, there is no need for a ridge board at all. Modern trussed rooves don't have a ridgeboard, just a batten nailed under one side of the rafters to hold the trusses the right distance apart at the top.

If you want a vaulted section of roof (ie without any ties) so that you can access the storage areas either side (this is what I did in mine), then you can have a hybrid system. Have ties preventing spread for most of the roof, and if necessary, a structural ridge beam over the void. The loads from this beam are taken by the complete trusses either side of the vaulted section. If you want a vaulted area of say 1.8m (ie leave out 2 ties), your ridge will need to be supported by 2 trusses each side, and therefore be 3m ish long. An orthodox 195x45 is plenty enough for that.

Can you offer any suggestion on what mix the concrete should be. Gen 3, C25 or 30, RC30 etc? Since I'd be putting mesh in shuld I be thinking about an RC mix or not bother for this installation?........

Personally I'd use a Gen 3, but you might ask Woody2Shoes, a structural engineer of this parish.

 

[DBT85]

........I'd really like as much open space above me as possible while also obviously having some storage up there. Right now the plan has a 195x67mm beam in there, rafters every 600/610mm to match the walls and I've also put ties in on every rafter for the sake of it with the top of each being 1/3 of the vertical height from the top of the top place to the top of the ridge. From the inner edges of each top plate the span is 6639mm. Again, I'm literally making things up so everything can and likely will change as required

The span is 6.6m? Don't you mean the ridge length? The span is at 90 degrees from that. The distance between the walls that the rafters sit on.

You're getting confused as to the role of a ridge beam. It exists only as one way of preventing spreading (the pushing apart of the walls). It serves no other structural function. Therefore, if you have ties at every pair of rafters as you show in your drawing, then there is no need for a ridge beam. Indeed, there is no need for a ridge board at all. Modern trussed rooves don't have a ridgeboard, just a batten nailed under one side of the rafters to hold the trusses the right distance apart at the top.

If you want a vaulted section of roof (ie without any ties) so that you can access the storage areas either side (this is what I did in mine), then you can have a hybrid system. Have ties preventing spread for most of the roof, and if necessary, a structural ridge beam over the void. The loads from this beam are taken by the complete trusses either side of the vaulted section. If you want a vaulted area of say 1.8m (ie leave out 2 ties), your ridge will need to be supported by 2 trusses each side, and therefore be 3m ish long. An orthodox 195x45 is plenty enough for that.

Can you offer any suggestion on what mix the concrete should be. Gen 3, C25 or 30, RC30 etc? Since I'd be putting mesh in shuld I be thinking about an RC mix or not bother for this installation?........

Personally I'd use a Gen 3, but you might ask Woody2Shoes, a structural engineer of this parish.

Sorry yes, ridge length. To me a span is just any unsupported gap in any direction.

I know if there are ties this regularly I only need a board, ideally I don't want ties this regularly. I'd love a section with ties for storage and then a further section with none at all for the open feeling offered. I've only put them in like this for the sake of it in the drawing, knowing that some will come out and that the beam/board would change. I also know a beam of 195x67 isn't near beefy enough for a ridge this long on its own so some kind of support is needed be that in ties or purlins etc. Right now I'm more inclined to go with ties where needed rather than purlins.

My plan was to have a hybrid system just like you did in yours but not knowing the dimensions required I just put the drawing together with a view to consultation and revision.

Given your example, a 195x45 3m long, what would be used for the rest, a smaller dimensioned board each end (say a 125x25), or just maintain the width and use a 95x45. How would it join to the 195x45?

Looking at the sizes I would like to look at removing maybe 4 ties giving me 1.8m storage either end and a 3m vaulted area and in my understanding then needing a 4.2m beam. This is all depending on the sizes required obviously.

 

[MikeG.]

If you use a ridge board then it should be that the length of the cut face of the rafter (the plumb cut at the ridge) is pretty much all in contact with it. In other words, if the length of the plumb cut is about 167 long, for instance (as it would be in a 30 degree roof with 145 deep rafters), then a 145 deep ridge is probably pushing it a bit. The next size up is 195, and that would be fine. 95 deep is never enough. It's about being able to get a fixing low down on the heel of the rafter to resist twisting.

 

[MikeG.]

.....Looking at the sizes I would like to look at removing maybe 4 ties giving me 1.8m storage either end and a 3m vaulted area and in my understanding then needing a 4.2m beam. This is all depending on the sizes required obviously.

The problem with this arrangement is the practical difficulty of erecting the ridge. You will need a scarf, and it can't fall over the the vaulted area or the two rafter positions either side. That 4.2m must be continuous. So, you'll need either 5.4m + 1.2m, scarfed, or you'll need 1.2m + 4.2m + 1.2m, including 2 scarfs. It's certainly not going to be very easy to erect either of those two arrangements alone.

 

[ScaredyCat]

Can't contribute to the building parts but,

• ethernet

Wont that require a trench? Why not opt for a Mikrotik wireless wire or Ubiquiti UBB both of which just require that you to point one end at the other and will provide you with a gigabit link?

You can plug an access point into either to provide localised wifi, if you need physical ports then a switch would do it nicely.

.

 

[DBT85]

Can't contribute to the building parts but,

• ethernet

Wont that require a trench? Why not opt for a Mikrotik wireless wire or Ubiquiti UBB both of which just require that you to point one end at the other and will provide you with a gigabit link?

You can plug an access point into either to provide localised wifi, if you need physical ports then a switch would do it nicely.

.

I have Ubiquiti stuff here for the wifi and would put one in the workshop once its built, but since I have to put a trench in of some kind to get power I might as well make it wide enough to put a separate Ethernet in at the same time and its a very easy connection to make. Wired is always best, that's why my house has 2 ports in every bedroom as well as the office and the living room, patch panel in the loft etc :lol:

 

[cookiemonster]

Can't contribute to the building parts but,

• ethernet

Wont that require a trench? Why not opt for a Mikrotik wireless wire or Ubiquiti UBB both of which just require that you to point one end at the other and will provide you with a gigabit link?

You can plug an access point into either to provide localised wifi, if you need physical ports then a switch would do it nicely.

.

I have Ubiquiti stuff here for the wifi and would put one in the workshop once its built, but since I have to put a trench in of some kind to get power I might as well make it wide enough to put a separate Ethernet in at the same time and its a very easy connection to make. Wired is always best, that's why my house has 2 ports in every bedroom as well as the office and the living room, patch panel in the loft etc :lol:

If you go for wired ethernet then make sure you lay at least one more cable than you need in case one gets damaged. The stuff is dirt cheap.

As to the windows discussion, I put double sliding patio doors in my workshop and they let more than enough light in. You can find them cheap second-hand.

 

[MikeG.]

Careful with that, though, as you have to balance the chances of a break-in against the increase in light. Sliding patio doors are renowned as an easy way in to any building.

 

[Inspector]

A tall narrow window lets in light without giving up much wall space letting you see out and can be barred or shuttered inside to keep the baddies out. Nothing you can do will keep determine ones out though.

Pete

 

[DBT85]

.....Looking at the sizes I would like to look at removing maybe 4 ties giving me 1.8m storage either end and a 3m vaulted area and in my understanding then needing a 4.2m beam. This is all depending on the sizes required obviously.

The problem with this arrangement is the practical difficulty of erecting the ridge. You will need a scarf, and it can't fall over the the vaulted area or the two rafter positions either side. That 4.2m must be continuous. So, you'll need either 5.4m + 1.2m, scarfed, or you'll need 1.2m + 4.2m + 1.2m, including 2 scarfs. It's certainly not going to be very easy to erect either of those two arrangements alone.

I'd not need to do anything like that alone so that's not a concern. Putting in 2 scarfs is more of a worry for someone who never done it before and doesn't want the roof to cave in on their heads but I'm sure I can manage.

Is the 195x45 you mentioned before for the 1.8m vault C16 or 24?

Can you give me an idea of the size beam needed for a 2.4m or 3m vault section?

While I'm at it, is there any need for the ridge to extend beyond the walls to create the overhang or can you just nail bits on the end as is done for the rest of the overhang?

Davies Timber which is near ish me list a treated 7.2m c24 8x2 for £48 and £76 for a 8x3. Useful to at least have one place in my pocket that nice and clearly lists that they an get it and can just order it direct on their site.

 

[DBT85]

If you go for wired ethernet then make sure you lay at least one more cable than you need in case one gets damaged. The stuff is dirt cheap.

As to the windows discussion, I put double sliding patio doors in my workshop and they let more than enough light in. You can find them cheap second-hand.

I always run 2 and in a case like there would be a draw cord in with both the ethernet and the electrical just in case. People who don't put cords in for later use are mad.

 

[ScaredyCat]

I have Ubiquiti stuff here for the wifi and would put one in the workshop once its built

UBB is also managed by the unifi controller would make for a nice integrated solution.


.

 

[flying haggis]

+1 as steve says for a water supply even just for an outside tap. as you will have a trench open anyway, bung in a bit of blue pipe.

As Mike says it's not quite as simple. For me to run the blue stuff (we have loads here kicking around) would be a lot more work as the supply is the exact opposite corner of the site. I'd have to lay a trench all the way around the house. I could run a cold supply in from the nearest bathroom with no real issue in some standard 15mm with a bit more ease.

in that case run from the bathroom in 15mm and change to blue as you leave the building. re a drain requirement ask steve maskery what he did for drains for his sink. i just suggested an outside tap if even just for watering that end of the garden/ using a pressure washer etc

 

[DBT85]

in that case run from the bathroom in 15mm and change to blue as you leave the building. re a drain requirement ask steve maskery what he did for drains for his sink. i just suggested an outside tap if even just for watering that end of the garden/ using a pressure washer etc

Can I ask why the change to the mdpe instead of just using polybutylene white stuff?

For my use case there would only be a use for a little water inside the workshop for washing my hands/cleaning things or drinking. The hose we have already covers the entire garden etc.

Yes it might be something that makes it in even if just for a belfast sink in one corner. But it will in part be decided by the drainage. Nobody we know in the area has a soakaway owing to the clay we are on. The remote houses like ours all feed into the drainage at the side of the road. We do actually have another large pipe added as a minor flood defence that could be tapped into but that's probably 40m away at the nearest.

 

[Fidget]

I have water running to my workshop with no drainage.

What I did was to get a very large (I think 40l) water container for camping which my sink (bought for £10 off Gumtree) runs into. Very easy to empty. I put a little bleach in after I empty it so it doesn't go nasty. I don't let it get too full or it is quite heavy.

To have water in the workshop is a boon, especially when you're in the middle of a glue up and need to keep rinsing your cloth out after wiping excess glue away.

Not rotated by me (hammer)

 

[flying haggis]

in that case run from the bathroom in 15mm and change to blue as you leave the building. re a drain requirement ask steve maskery what he did for drains for his sink. i just suggested an outside tap if even just for watering that end of the garden/ using a pressure washer etc

Can I ask why the change to the mdpe instead of just using polybutylene white stuff?

For my use case there would only be a use for a little water inside the workshop for washing my hands/cleaning things or drinking. The hose we have already covers the entire garden etc.

Yes it might be something that makes it in even if just for a belfast sink in one corner. But it will in part be decided by the drainage. Nobody we know in the area has a soakaway owing to the clay we are on. The remote houses like ours all feed into the drainage at the side of the road. We do actually have another large pipe added as a minor flood defence that could be tapped into but that's probably 40m away at the nearest.

the op mentioned running from the bathroom in copper (all the way??) but yes the white polybutylene would be ok and as with blue pipe is one continous length and would be easier as it is all push fit(wonderful stuff, used it for years)

 

[DBT85]

in that case run from the bathroom in 15mm and change to blue as you leave the building. re a drain requirement ask steve maskery what he did for drains for his sink. i just suggested an outside tap if even just for watering that end of the garden/ using a pressure washer etc

Can I ask why the change to the mdpe instead of just using polybutylene white stuff?

For my use case there would only be a use for a little water inside the workshop for washing my hands/cleaning things or drinking. The hose we have already covers the entire garden etc.

Yes it might be something that makes it in even if just for a belfast sink in one corner. But it will in part be decided by the drainage. Nobody we know in the area has a soakaway owing to the clay we are on. The remote houses like ours all feed into the drainage at the side of the road. We do actually have another large pipe added as a minor flood defence that could be tapped into but that's probably 40m away at the nearest.

the op mentioned running from the bathroom in copper (all the way??) but yes the white polybutylene would be ok and as with blue pipe is one continous length and would be easier as it is all push fit(wonderful stuff, used it for years)

I am the op

Wouldn't run it in copper. Poly all the way for that kind of job. It certainly has its uses.

 

[DBT85]

Mike,

Can you give me an idea of the vault a 2x8 c24 or a 3x8 c24 can give me?

Is the 195x45 you mentioned before for the 1.8m vault C16 or 24?


In other news my brother has asked me to draw him something for framing the inside of his brick garage for a home office so I'm getting to use Fusion 360 for something. I've even done it all "properly" so I can change one parameter like stud depth or wall length or something and the whole thing just adjusts accordingly. Very nice. I can take what I'm learning with that onto this project.

I am now Furloughed for at least April and May so I have time to kill!