Patio To Office Remodel

balanceact

I've got a nice potential little remodel coming up but I'm not sure how to work out the foundation/flooring problems.

See pictures..

The owner wants this pebbled concrete patio enclosed into an office. There are no plans available so I am not sure how that main corner is supported. The little extra footing under one of the 4X4 posts looks literally extra and leaves me suspicious but there are no cracks in the pad or sidewalk which would indicate settling problems. This corner is supporting a good section of the roof and the enclosed ceiling of this patio space. (The sag in the outside over hang is a separate problem.)

I doubt the patio has plastic under it so once it is enclosed I'm concerned that the concrete could wick moisture into the small cross spaces under a new floor.

I'm thinking of laying down some 6mil plastic and then put my mud sills on top of that and concrete screwing them through the plastic to the concrete pad. I don't know how thick the pad is but I suspect at least 4 - 6" because of the height of the pad above the side walkway). I don’t want to put in regular foundation anchors into the pad because I don’t want to go through it to the dirt or crack the outer edges of it.

It has been suggested to me to put a mud sill under each floor joist for better support rather than just put a middle long mud sill running across the middle of the floor. Then put a little round attic vent in each joist space so each space could "breathe".

I'm not planning on adding any additional foundation work because the two outside walls I'm building will only be holding up themselves. Cutting into the existing pad to lay a foundation for non supporting walls seems pretty excessive. Although it is probably what code would require, I don't think my clients want to spend the extra money.

Another concern is how to deal with the two expansion joints that will run in the concrete pad from the new room to outside. Even though they are sloped water could wick into the new sub floor area through these redwood 2Xs..

I'm curious to hear any advice on this foundation/floor problem. Once I get this resolved, (and move the air conditioning unit) the rest of the installation should be pretty straight forward.

thanks, balanceact

Attached Thumbnails

   

dkillianjr

Its hard to tell from the pics, is the roof sagging or the overhang? What is holding up the roof? In the pics it looks like I can see the rafter tails.


Dave

orson

The rake is probably just attatched to the gable end instead of cantilevered over gable wall.

I'm a little lost....You're saying there are no footings and you won't be putting any in? How are you going to build non-bearing exterior walls?

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TimelessQuality

I'm totally lost...
You talk about floor joists, but it looks like the slab's on grade with the floor now????????

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balanceact

dkillianjr - The overhang is sagging; it's unsupported at the bottom end and the weight of it has over time caused it to sag. But that's a separate issue which doesn't concern me at the moment. There are various ways to fix that.

Orson and Timeless - I'll be building walls between the corner posts and the house, a short wall paralleling the sidewalk and a long wall paralleling the present exterior of the house which will close in the approximately 7'X17' patio under the roof. There will be one window in the small side wall and windows and door in the long wall.

I'll lay down mud sills between the posts and either another long mud sill between the house and the what will become the outside wall to support my new floor joists or mud sills under each floor joist. The new joists will have to be perpendicular to the existing wall and account for the little slope that exists so the new interior floor will be level.

The present concrete pebble pad starts about 5 1/2" below the interior floors. If you look under the French doors you can see that space.

I could cut open a hole in the slab and check to see if the perimeter on the sidewalk side has a stub foundation wall. I don't really see why there would be any foundation supporting the portion of the patio slab that is under the house roof. I would hope there is some real foundation support of those odd three corner posts, that corner is taking a lot of weight from the roof and closed in ceiling over the patio, but I wonder why one of them (not the central real corner one) has its own pier support. That corner looks fishy..

The walls I would put in between the supported corner running on the side back to the house and along the front under that main 4X12 would only be supporting their own weight.

Are you two suggesting it is necessary to cut open the slab and add footings for these walls??

Even if I do that I'm still concerned about moisture coming through the slab (I doubt, but don't know if it has a vapor barrier beneath it. Since it was designed as an exterior slab not the interior slab of a slab foundation, I wouldn't expect any of the patio concrete to have a vapor barrier.)

Does this make my problem clearer to you two?

1) Is a foundation really necessary for the two new non weight bearing walls?

2) How do I keep moisture from coming through the concrete under the new floor I would be building. Would the little vents be enough to air out that tight sub floor space?

balanceact

Alwaysconfusd11

I would be more worried about that corner post, or 3 corner posts, I cant really decipher that corner from the 2 angles you show. What is the size of the beam between the house and that corner that the rafters are sitting on? Why not so it right? Eliminate that beam with the funky corner post, throw down a foundation, frame the 2 walls supporting the roof, cantilever a beam out to support the eve.

thom

Slot the concrete pad, excavate proper footings/stems, form and pour a curb height that matches the existing floor height, rip sleepers for the floor to sit on top of the slab so that your new floor height matches the existing. Framing the exterior walls to the rafters on proper foundations will allow you to solve the existing sagging rafters/joists.