Post on a concrete base at a 45-degree angle?

[samuel99]

Hello!

I'm going to build a conservatory, and the reason I'm not placing the thread there is that this is not specifically about conservatories but more a question about "best practices" when it comes to beams, plinths, and angles.

The conditions are as follows:

• The conservatory will stand on a deck floor and plinths.
• I've purchased a pre-made laminated timber frame from Willab Garden.
• It comes with posts that are designed to extend to the corner, see picture.

I have chosen a conservatory with a broken corner and am now considering how best to support the load from the corner post. The corner post is to be placed on double 45x170 joists that are then attached to the plinth.

But how do I place a plinth precisely in a 45-degree angle? How is this usually done?

I have two suggestions myself:

• Place two plinths in each corner, see option 1
• Somehow move the posts slightly in on each side so that one post per corner is sufficient and build out with joists to reach the angle (purple), see option 2.

 

[Stefan1972]

if you build the floor as it should be done, the conservatory won't know how many plinths there are or where they are placed, right?

 

[samuel99]

if you build the floor as it should be done, then the sunroom wouldn't know how many piers there are or where they are located?

I don't quite understand what you mean... But the goal is to take the load as straight down as possible. I don't want to place a post supporting the front beam and roof right between two piers. Or am I misunderstanding you?

 

[Stefan1972]

If you build the floor in roughly the same shape as the patio room and have footings at about the intersections in question, it is just a matter of calculating the footings and joists based on the weight of the patio room. There is nothing that says the patio room's frame must extend directly into the ground unspliced.

 

[vectrex]

I have built a friggebod using the same principle. I placed the plinths a few decimeters away from the corners. I connected the beams with screws and sturdy angle brackets.

 

[samuel99]

If you build the floor in roughly the same shape as the conservatory and have the footings at approximately the intersections it's about, it's just a matter of calculating the footings and joists based on what the conservatory weighs. There's nothing that says the conservatory's frame must go unsupported all the way down to the ground.

Of course, I can size the entire deck so that I can take the load from the conservatory anywhere, but nobody builds like that, right? It sounds both unnecessarily expensive and, above all, unwise. If I can take the load straight down, then the need for heavier material naturally decreases.

 

[samuel99]

I built a garden shed according to the same principle. I placed the plinths a few decimeters away from the corners. I joined the support beams with screws and sturdy angle irons.

Do you mean with double plinths in each corner (option 1) or just one (option 2)?

 

[Stefan1972]

Well, I didn't mean it should be something extreme, but it should reasonably be enough with one block at each intersection. Not like two as you're suggesting.

 

[vectrex]

Do you mean with double plinths in each corner (option 1) or just one (option 2)?

No, single plinths. One in each corner!

 

[Finndjävel]

A pedestal on each side is more than enough. Don't make it so difficult for yourself.