A Lean-To Tale (with pics & maybe vids)

Jack_regan

dnme wrote: »

With regard to damp proffing the bottom ends of the timbers, I have been thinking about this also. If I put a dpc under the posts, this might act as a water retainer for water that flows down along and through the posts. So I am wondering would I be better off resting the timber on some sort of stand-off? The outer posts will sit in metal surrounds that ar ebolted to the ground. These have drainage holes in each corner and I might lift the timbers an inch inside them, but what to rest it on? What about a shovelfull of pebbles?

With regard to the wind, I have taken it into consideration from the start. I am over-engineering the job because of it.

The mitred posts are probably fencing posts with the top cut at an angle to allow rain top flow off. I am told that the local BP wouild not have any other 4x4 types in that length. I'll ring them monday morning and double check. Might also ring around a few others.

Ah that explains it alright, fence posts up my way are usually mitred on both sides to a point for driving into the ground. There is a slight chance that the bp might have 16 foots or 4.8 metre lengths of 4 by 4 that you could cut in half, it's an unusual size though and they're more likely to have 4 by 3 or 6 by 3 in 16 fts.

With regards to the timber uprights and damp proof course, I had the same concerns as you when we were putting in the timber frame for the door on the house, I ended up sticking a piece of lead to the bottom of the timber door frame with tech 7.You can buy lead off a roll by the foot.(ie. you don't have to buy a full roll.) It seems to be working. It's mainly the rising damp that you want to stop with the dpc. I know there is a risk of water pooling in the dpc but it will dry eventually with the wind/sun.

I've not come across anybody using pebbles as a dpc before, but that doesn't mean it won't work, you could be on to something there.

I know you're over engineering the structure, just don't trap the wind, that's all. The wind needs to be able to escape but sure you know that yourself.

Jack_regan

dnme wrote: »

Yeah, just the outer 4x4 posts, definately treated. I'll slap some preservative on the rest. I'd like to have a tin handy during cutting and construction to paint all the insides of joints etc. What would you recommend?

Protim wood preservative.

TopTec

Any proprietry preserver, Sadolin is very good, cuprinol is fine but any will do - waterbased preferably. I know Lidls have been doing some german stuff - no idea what its like.

I would stand all your uprights in a shallow tray of the preserver to get a good penetration prior to erecting..

Forget the Dpc, if you have drain holes in the fixings, that will be fine. Dpc isn't designed for that application. Standing the posts on gravel or pebbles will make no difference. As long as they don't remain in water they will be fine.

My Uncle, a fencer, used to soak the bottom third of the posts in creosote. let it go off then stand the posts in a burning brazier for a few minutes. The outside layer of wood, burnt, would seal in the creosote and prevent water ingress.

He swore to me that any post put into the ground prepared this way would last 25 years!!

TT

dnme

@TopTec

Many thanks. Why water based specifically?

TopTec

Non-Toxic, good penetration, usually animal friendly.

TT

dnme

TopTec wrote: »

Non-Toxic, good penetration, usually animal friendly.

TT

Ah ok, I could never figure out how water based stuff prevents or protects against.......well water! ???

Jack_regan

I've used the some of the sadolin products before and found them to be good. The ones I was using were not water based if that's important to you. They are expensive though especially compared to the stuff you'll get in lidl.

http://www.sadolin.co.uk/global_assets/pdf/datasheets/WoodPreserver.pdf

I'm not sure about the cuprinol stuff, I've never used it.

Anyway just making sure you're aware that all of these preservers are only recommended for above dpc level. Top Tec is right about dpc not being designed for you're application but I'd always favour having some kind of dpc if at all possible. It sounds like the fixings you are using might be holding the uprights up off the slab anyway which means you can forget about the dpc.

You can't get the creosote stuff anymore, there is stuff called creosote substitute which probably does exactly what it says on the tin.

Definitely worth soaking the uprights in whatever preserver you decide to get, good advice there. (the longer the better)

Have you decided what your using for fixing? (screws, nails, coachbolts etc)

dnme

Jack_regan wrote: »

Have you decided what your using for fixing? (screws, nails, coachbolts etc)

all of these.

TopTec

Just one other point I would make dnme, about the physical fixing of the structure to the house.

Due to lateral movement of the structure on it longside away from the back door, the lateral roof members will have to be fixed to the house above and to the left of the back door. I see your plan is to butt these members underneath the existing soffits but not against a wall plate, or length of timber fixed to the wall.

I would suggest, in that case, you use something like joist hangers to fix the roof joists to the wall.

TT

dnme

TopTec wrote: »

Just one other point I would make dnme, about the physical fixing of the structure to the house.

Due to lateral movement of the structure on it longside away from the back door, the lateral roof members will have to be fixed to the house above and to the left of the back door. I see your plan is to butt these members underneath the existing soffits but not against a wall plate, or length of timber fixed to the wall.

I would suggest, in that case, you use something like joist hangers to fix the roof joists to the wall.

TT

Yea TT, My plans dont include any fixings, too complicated to draw. But I intend to brace somehow. it might be too tight ot get a beam up there, if so, I'll try L brackets under the cross members or something else.

slimjimmc

TopTec wrote: »

Just one other point I would make dnme, about the physical fixing of the structure to the house.

Due to lateral movement of the structure on it longside away from the back door, the lateral roof members will have to be fixed to the house above and to the left of the back door. I see your plan is to butt these members underneath the existing soffits but not against a wall plate, or length of timber fixed to the wall.

I would suggest, in that case, you use something like joist hangers to fix the roof joists to the wall.

TT

Yeah, was just thinking that too, perhaps run a larger joist along the outer edge similar to the short one over the house extension to stiffen the structure even more.

dnme

Folks, as you may know, the back yard falls away from the house by about 4" on the outside. I know it doesn't sound much, but it looks and feels like a substantial angle, especially if you stand on it. So it occurs to me that my post surround brackets will not be level. Just went out, positioned one and photographed it. It is indeed, way off level.



How would you solve this. I need to put something under the bracket along its outside to level it, could I use washers? what do you think?

TopTec

Well, you effectively have only two options - Shim the outer edges with washers, you wont need much to level them.

Or cut out a socket on the slab for the brackets to fit in, then using a strong mix of mortar fill the socket hole so that it is level.

TT

dnme

TopTec wrote: »

Well, you effectively have only two options - Shim the outer edges with washers, you wont need much to level them.

Or cut out a socket on the slab for the brackets to fit in, then using a strong mix of mortar fill the socket hole so that it is level.

TT

Oh yeah, so I'd be kinda burying the bracket. That sounds more robust but the washers are far simpler and less work.

EDIT: Cutting out a socket might leave me with pools where water gathers also.

The angles I'm dealing with are tiny but make a big difference over lengths and they effect square. The angle that the concrete falls is 2 degrees from level. If I were to place the rafters parrallel to the ground, they'd meet the wall at 88 degrees, I'll add another 2 or 3 degrees to their fall off.

dnme

Another question for those in the know, If might decide to add extra bracing to the old walls by rawl bolting the uprights to it. I would probably need to try a few different locations with the drill before I lfelt like I was into solid stone (the walls really are bad). So lets say, I find a couple of good spots, drill for my rawl bolt, fix the bolt etc. How do I then locate the holes to be drilled in my upright accurately?

2 stroke

I'm sure your landlord wont be happy with you making a pin cushion of his walls. Decide where you want support, then drill through the timber into the wall. Then deal with whatever you find in the wall at that point, I suggest chemical fixings/ threaded bar.

TopTec

dnme wrote: »

If might decide to add extra bracing to the old walls by rawl bolting the uprights to it.

Just a thought. If you are going to do this dnme then fit a wall plate. This then gets rid of the need for most of the uprights and you can drill through the plate along its length to find a solid fixing.

This gives you a far easier product to fix your roof to.

TT

dnme

TopTec wrote: »

Just a thought. If you are going to do this dnme then fit a wall plate. This then gets rid of the need for most of the uprights and you can drill through the plate along its length to find a solid fixing.

This gives you a far easier product to fix your roof to.

TT

TT, whats a wall plate, whats it made of ?

Landlord didn't really want the wall to have to bear the weight, so we agreed on uprights strapped to the wall. These will bear the weight. What I want to do is add extra bracing by rawl bolting them to the wall. The wall is very old stone covered in a coat of pebble dash. It's really poor to drill into so I would need the ability to have several goes with the drill before I found good solid stone.

2 stroke

dnme wrote: »

I would need the ability to have several goes with the drill before I found good solid stone.

If the wall is that bad, you are better off making a good chemical fixing into a forgiving part of the wall than to anchor into a stone that your structure is going to shake loose.

dnme

2 stroke wrote: »

If the wall is that bad, you are better off making a good chemical fixing into a forgiving part of the wall than to anchor into a stone that your structure is going to shake loose.

Are those chemical fixings that strong? We're talking about the glass inserts right ? On another note, I've just been up to the attic and notice a line or two of new blocks along the top of the wall, so a cross beam bolted to that is again an option. I should have inspected that from the getgo but landlord was insistant.

Weather is bloody awful. Rain all night and now heavy drizzle all day. No end to it. All my timbers are out in the garden on three pallets with dodgy leaky tarps over them. There's no avoiding the timber getting wet.

TopTec

Ok, a wall plate is a beam of wood, usually 4 or 3 or 5 by 2" that sits on top of a wall which forms a load bearing surface that you nail the rafters or trusses to. The rafters having been notched (or birdsmouthed) so that the weight of the rafter sits atop the plate.

The joists, forming the base of a roof triangle, prevents the rafters spreading apart.

A wall plate can also be fixed to the face of a wall, near the top. Then the horizontal timbers that you intend will carry the plastic sheeting, will screw or nail into or onto this wall faceplate.

If you have enough room then bolt or screw it to the concrete blocks that you have found. You could use three plates on your build - either side of the "extension" and then to the left of the back door. (This one is slightly more difiicult as it has to mirror the fall of your slab).

To aid stability I would half joint the ends to sit on top of your plate and then screw or nail through the rafter end to the plate.

I have an old cottage, and when I was fixing new guttering to it the most atempts I had to find a fixing point for a screw was three.

Simples

TT

dnme

TopTec wrote: »

Ok, a wall plate is a beam of wood, usually 4 or 3 or 5 by 2" that sits on top of a wall which forms a load bearing surface that you nail the rafters or trusses to. The rafters having been notched (or birdsmouthed) so that the weight of the rafter sits atop the plate.

The joists, forming the base of a roof triangle, prevents the rafters spreading apart.

A wall plate can also be fixed to the face of a wall, near the top. Then the horizontal timbers that you intend will carry the plastic sheeting, will screw or nail into or onto this wall faceplate.

If you have enough room then bolt or screw it to the concrete blocks that you have found. You could use three plates on your build - either side of the "extension" and then to the left of the back door. (This one is slightly more difiicult as it has to mirror the fall of your slab).

To aid stability I would half joint the ends to sit on top of your plate and then screw or nail through the rafter end to the plate.

I have an old cottage, and when I was fixing new guttering to it the most atempts I had to find a fixing point for a screw was three.

Simples

TT

Yeah that's what I'm sorta planning. "Wall plate" = beam.....simples.:D I'm gonna have to stand a couple of uprights there at the extension to carry the rafters there. They will need to stand out form the extension wall to clear the facia and gutter. Can you recommend any way to secure these uprights to the extension wall (which I believe is new block)? They'll be a foot out from it.

TopTec

To be honest I wouldn't get any more complicated than your plan on the second page of the thread.

The only way of bracing the two uprights in front of the extensionas far as I can see, is some horizontal braces that are fixed to the sides of the extension and protruding out the distance you want where they bolt to the uprights.

In your position I would do as you plan then it will become obvious whether you need any braces anywhere on the structure.

Brickwork between the uprights will certainly stiffen it if needed....!!!:):) or is that for a seperate thread.;)

TT

dnme

Many thanks everyone. You know I might go with chemical anchors throughout. Even bolting down the post surrounds. I really like the idea of non-compression and 100% surface area grip. Have any of you ever used them? Would local BP have em? Any recommendations?

dnme

TT

Nothing is simple. You can see the two windows and how close they are to the top of the wall. There is only 3.5" to the reveal and the reveal is 4". The reveal also jutts out form the wall about .5" on a slight taper. So I dont know what to do. Should I run the one wall plate and try and joint it in around the window, or run two wall plates. And what in gods name will I do with the window beside back door (pic 1). I guess it's gonna be a suck it and see job. Its very complex, nothing is square and a big strom forecast for tomorrow. (Might head up to Mullaghmore and watch the sea...spectacular).

TopTec

With the right hand window I would put a plate either side and adjust your uprights to match.

With the left window I don't see too much of a problem. Just continue the free standing nature of the roof sheets from the extension over the window and door. You could run another shorter rafter towards the window parallel with the rear door that would carry the sheet if you thought it was too flexable.

As you say, with bespoke structures of this kind, and I have built a couple of em, you plan ahead as much as possible but accept it needs fine tuning as you go.

You have already demonstarted you are a bit crazy so what a couple of odd corners between friends!

I am off to Killala tomorrow to walk the small beach with the dogs, the seals there will be keeping a low profile!

TT

2 stroke

dnme wrote: »

Are those chemical fixings that strong? We're talking about the glass inserts right ?

If the wall is as bad as you say, they are stronger than the wall.
I wouldnt use glass inserts except in concrete or stone, infact stopped using them altogether about 2 years ago.
You can now buy a 2 part mix that works in a caulking gun with a mixing nozzle, you can pump as much as you need to in each hole. You have to work fairly fast, have all your holes drilled beforehand, or the mixing nozzle will clog.
Don't forget to blow all dust out of holes, I often use an airline attached to a spare tyre. Also give the threaded bar a good spin in the wall. Do not tighten too soon, we usually leave them a few hours

dnme

2 stroke wrote: »

If the wall is as bad as you say, they are stronger than the wall.
I wouldnt use glass inserts except in concrete or stone, infact stopped using them altogether about 2 years ago.
You can now buy a 2 part mix that works in a caulking gun with a mixing nozzle, you can pump as much as you need to in each hole. You have to work fairly fast, have all your holes drilled beforehand, or the mixing nozzle will clog.
Don't forget to blow all dust out of holes, I often use an airline attached to a spare tyre. Also give the threaded bar a good spin in the wall. Do not tighten too soon, we usually leave them a few hours

Many thanks 2S.

Just read up on them this evening. They are epoxy or poly resin based which is gas cos I'm up to my eyes in that stuff working on the boat that this shelter will cover.

dnme

2 stroke wrote: »

If the wall is as bad as you say, they are stronger than the wall.
I wouldnt use glass inserts except in concrete or stone, infact stopped using them altogether about 2 years ago.
You can now buy a 2 part mix that works in a caulking gun with a mixing nozzle, you can pump as much as you need to in each hole. You have to work fairly fast, have all your holes drilled beforehand, or the mixing nozzle will clog.
Don't forget to blow all dust out of holes, I often use an airline attached to a spare tyre. Also give the threaded bar a good spin in the wall. Do not tighten too soon, we usually leave them a few hours

Hey 2 stroke (or anyone).

Tell me, what size hole should be drilled for a specific bar. Say I'm running in 16mm threaded bar, will a 16mm drill bit do, or do I need a bigger bit to leave a bit more space for the resin?

Also, there's mention of insert bags for hollow walls. I guess to retain the epoxy as it's poured in. Have you come across these? Where to get em?

cnocbui

2 stroke wrote: »

Hi dnme, I am considering a similar project myself so will be following this thread with interest. I plan to use multiwall polycarbonate, so if you find a cheap source of this, let me know.

I bought some stuff for my project from here:
http://www.rockwell-meriden.co.uk/shop/category.asp?c=25&desc=Multiwall_Polycarbonate_Sheet_Special_Offer_Multiwall_-_Stock_Sheet_Sizes