How to replace supporting posts?

[Russ42]

I have discovered the posts holding up the roof at the front of the house have rusted off at the base. There are 5 all up but I have started on 2 which are the worst. They are spaced about 2.4m apart and have a set of sliding doors between them and windows on each side, all floor to ceiling. My plan is to cut them off near the top and have new galvanized bases welded on (these have been fabricated and are 1.9m long). Originally, the posts were set onto Hebel Powerpanels. The outside is a verandah with a slurry of concrete sloping to the outer edge. This means the top of this is higher than the inside of the house and the base of the posts. My plan is to set the new post about 40mm higher and also move the door set and the window sets up 40mm. This will create a "hob" (?) which should keep the water from entering the house. What should I use under the posts to make up that 40mm? Any other suggestions? Builders don't call back.

[MitchellMc]

Hi @Russ42,

It sounds like you could use Sika Grout 20kg HES High Early Strength Structural Grout to create 40mm pads for the posts to sit on. However, I have concerns about how these posts are connected at the top and bottom. It might be difficult to consult with a professional, but I certainly would to understand better if the fix you propose will be successful. 

Is this a structural wall? If so, all the more reason to call in the professionals.

Let me tag @Nailbag and @Dave-1 to see if they have any thoughts.

Please let me know if you have any questions.

Mitchell

[Dave-1]

Afternoon @Russ42 

Before you start I would be installing some support props to support the span. I know Bunnings sells them. Gorilla 1.98-3.35m Galvanised Formwork Prop #2 

I am hesitant on the fix you are descibing mostly because you are attaching via welding a new bracket to an existing bracket that may have shifted in height already due to the 5 supports rusting. 

I would strong suggest wait to for a builder to give a quote for this particular job. 

My main concerm is that the sliding doors and windows are carrying the load across the width of the house. I have a "sag" across my sunroomn at the back of the house and when I fix it the whole wall will be done in one go (via a builder as it is outside my level of knowledge) I will be helping them for sure but I am a sparky, not a builder so will err on the side of caution.

Dave

[Russ42]

Thanks Mitchell. The builders I have tried to contact are not interested in answering the phone or calling back. Not just for this job but also a previous couple. Thanks for the recommendation of the Grout. I am guessing the tops of the posts are fixed to the RSJ with bolts and the bottom with Gal screws into the Hebel. I have no faith in the builders as the posts are not Gal and we are opposite an ocean beach. Also there is no flashing on any of the external doors or windows, plus other issues I am dealing with. My intention, with consultation with a welder I have found, is to put a slieve in the posts at the joint to add support and make the weld stronger. The base I intend bolting down with Gal screws into the Hebel with epoxy glue ( I used it before ). 

re. the base for the 40mm hob. I was thinking of strips of fibre cement sheeting with a grout between. Perhaps 2 at 20mm thick. I was thinking of putting the posts onto these but I like the idea of your Sika Grout. Perhaps I will use the Sika Grout as a step for the posts and put Fibre Cement sheeting under the doors and windows.

[Russ42]

Thanks Dave, I have covered some of your concerns in my reply to Mitchell above. I have 2 Acro props from Bunnings ready to go. I intend checking for sagging but have not yet worked out how. Am thinking string line.

[Dave-1]

Afdternoon @Russ42 

Ideas are only ideas, you are the one whoose place it is. Its why I like this page so much. Every different point of view is more data, either for solidifying what you want or making sure what you want is ok in your mind.

Id go laser line if possible as string lines ive never had a lot of trust in over a long distance.

Dave

[Russ42]

Was thinking the same (laser line). I think I have one on a saw although a larger one may be handy.

[JacobZ]

Hi @Russ42,

Just to jump in on the conversation, I can personally vouch for this Lasertec 3DG Ultra Multi-line Laser as I own and have used it extensively. 

However, any laser level, particularly green line laser levels, which are much better outdoors, would work. This Ozito 20m Green Cross Line Laser LCL-20G should be a perfect cost-effective option for this job.

Jacob

[Nailbag]

Hi @Russ42 

Understanding the frustration of dealing with trades not calling you back, but this is a structural issue as @MitchellMc mentioned. Your choices are either to battle away trying to get a "registered" builder or the other option is to employ a draftsperson who has the qualification to advise on what the fix would be. You can then decide if thats something you can rectify yourself under their guidance or with the help of a handyman/carpenter. Ultimately my advice would to not tackle this yourself with either of those two options.

Nailbag

[Russ42]

As Ricciardo would say, Nailbag: "understood".....