enclosing an existing porch

[arbitrary]

I'm looking to enclose an existing front porch by building a dwarf wall (single skin brick) and then installing windows and a door. A photo of the existing porch roof is below.



My initial thought was to maximise the size of the porch by lining up the brickwork and windows vertically with the inner edges of the existing fascia boards. Yesterday I removed part of the existing cladding underneath the roof to better understand its construction. A photo of the frame is below.



The construction of the frame suggests that I ought to line the brickwork and windows with the frame so the porch will be a few inches smaller than planned. Do folks concur with this?

Also, I would like some advice on supports posts and how the windows "connect" to the roof's frame.

As I want to eventually remove the gallows brackets I'll need 4 support posts, one at each corner. I'm struggling to find anything suitable online. I'm thinking of an aluminium or steel box section tube covered in uPVC with a screw type adjuster on one end?

Should the tops of the windows fix directly to the timber frame of the porch roof or should there be something else in-between?

 

[piper64]

Your porch roof is probably well fixed to the house wall as it is. How are you going to fit the windows? Are you building up to the existing roof with blocks, incorporating windows or fitting upvc windows to entirely fill in between the roof and the proposed porch wall?

Mine 'fill in the gap' between the dwarf wall and the wooden roof structure. They are screwed to the roof structure, corner posts and the house wall but not the sill. The corner posts are screwed to the frames either side of them and rest on the reinforced sill.

Here's mine in the attached picture.

If blocks, they will support the roof. If upvc, you need to specify reinforced corner posts that slot onto the upvc window frames and reinforced sills. Just the outer two corners should be fine, as long as the existing wooden framework is secured to the house wall securely. Mine was, but I still added a sturdy wooden wall plate for added security as well as fixing straps to the wall/wood.

 

[arbitrary]

Thanks for the reply. I intend the build the single skin brick wall up about 14 courses and then the rest will be windows. Unlike your porch the door will be offset to the left side to line up with the existing house door.

The existing roof frame work is nailed to the house wall with what I think are called clout nails?

 

[piper64]

It will probably be OK as it is, but you could reinforced the framework to the house wall with wall bolts. If the structure is not secured to the house wall, the weight of the roof will be more at the furthest edge away from the wall, with a potential 'hinge' effect where it's lower edge meets the house wall.

Why single skin? If you need to do that for space saving, then make sure that you have some means of insulation/damp proofing such as a drywall on the inside. Our existing outhouse extension was built by the previous owner and is single skin. The cold and damp come straight through.

 

[arbitrary]

The rationale for single skinned is that the existing door is too close to the side of the the roof structure meaning there isn't room for a cavity wall. In the first photo you can see how close the left gallows brackets is to the edge of the brickwork.

The porch will be used as a vestibule allowing outdoor footwear to be taken off as well as a place to put wet coats and brollies etc. And to dry off the puppy that might join us. It not being heated and therefore perhaps a bit damp shouldn't be an issue. I was thinking of speccing trickle vents in the windows for just that reason.

 

[piper64]

Makes sense, but a bit of damp is more than an issue than you would believe. During these drier spellls, it's easy to disregard it. I'm sure there must be a space saving insulation method to hold it at bay, but others will chime in perhaps?

 

[arbitrary]

The brickie advised that some damp would come through the brickwork from the outside - I figured a few coats of Thompsons waterseal or the like would help with that. The porch is on the north side of the house meaning the walls wouldn't get as wet as on the south or west side but at the same time there's no sun except this time of year.

I suppose a cavity wall is possible but there would be a deep cill outside and no cill inside - that would look a bit odd?

 

[piper64]

If it was a cavity wall the window frames would sit on the inner edge of the outside leaf, so the outer sill would not be deep, but you would have a sill on the inside too.
If you want to keep inline with the existing roofline without reducing the area inside the porch or if the doorway prohibits a cavity wall, a single leaf is the only option so finding a good way to reduce damp is going to be your focus.

If a brickie is doing the work, he'll advise what to do.