New strip footing next to old

[prof_montoya]

Hi all,

Doing a home extention. In one part I just need to push out the wall 300-400mm (wall needs to be rebuilt and little more space for a stairwell). Current house is on strip footings. Question - is there anything I need to keep in mind when adding a new section of strip footing right next to and running parallel to an old footing. I personally wont escavate or pour concrete however as owner builder want to make sure I know what to expect.

Also - which trade is responsible for ensureing existing house floor level is maintained through to the new extension? Is it the concreter when he pours footings (and concrete piers??)? Or, bricklayer when he bricks up the sides to subfloor (and brick piers)? Or carpenter when he puts up the frame and subfloor?

Thanks
Carlos

[Gaza]

Hi all,


Also - which trade is responsible for ensureing existing house floor level is maintained through to the new extension? Is it the concreter when he pours footings (and concrete piers??)? Or, bricklayer when he bricks up the sides to subfloor (and brick piers)? Or carpenter when he puts up the frame and subfloor?

Thanks
Carlos

this comes down to you as the builder to set out your heights & know what RL's you need for each item.

i suggest you draw full size on a off cut of ply the thickness of the finsh flooring, then joists, beares, brickcourses & top of footing, you can then nail this to the fence at the correct height & transfer heights off this so that everyone knows what is going on. concrete can be a bit lower as the first course of bricks can have more than 10mm motar but you dont want the heights so bad that you are cutting bricks in half.

[prof_montoya]

Thanks Gaza.

Basically what you're saying is I have to tell the concretor what level go by when pouring the footing. Can I assume present day timber flooring and joists and bearers will be the same as used in the original house (1940s) so maybe I can just take my levels from those and existing bricks? Or do I need to consider current size of timber and/or engineers calculations - still being finalised.

Also, do I (or should I) put down yellow tongue flooring first below solid timber floor? I'll need to factor this in. Is it standard thickness or varies from mfg and supplier?

PS What do you mean by RL's? Also there wont be a fence as I got to pull it down since I'm building on the boundary. I guess I can just put it on side of existing house where extension will begin

thanks
Carlos

[barney118]

You could find yourself in trouble with councils building on the boundary, have you checked with them?

[Gaza]

Thanks Gaza.

Basically what you're saying is I have to tell the concretor what level go by when pouring the footing. Can I assume present day timber flooring and joists and bearers will be the same as used in the original house (1940s) so maybe I can just take my levels from those and existing bricks? Or do I need to consider current size of timber and/or engineers calculations - still being finalised.

Also, do I (or should I) put down yellow tongue flooring first below solid timber floor? I'll need to factor this in. Is it standard thickness or varies from mfg and supplier?

PS What do you mean by RL's? Also there wont be a fence as I got to pull it down since I'm building on the boundary. I guess I can just put it on side of existing house where extension will begin

thanks
Carlos

RL= reduced level.
new josit & bearers sizes depend on if you use hardwood or LVL's or I beams, suggest you use red alert.
if using T&G flooring you should lay yellow tongue that floor baords are laid over.

suggest you get a builder on board or a carpenter that can act as a foreman to help you out

[prof_montoya]

Hi Barney - I have checked with council and building on the boundary is OK.

Gaza - waiting for engineering to confirm joist and bearer sizes. Will then use this to calculate RLs

PS - given I am extending an existing room and not "adding" a new room, my preference is to not use yellow tongue because the existing floor in the room doesnt have it.
However will use it in upstairs rooms as these are all new

Carlos

[Bloss]

As Gaza says you are the builder so you are responsible for all the stages of construction - the tradies you sub-contract might or might not have the knowledge, capacity and willingness to do what is needed, but in many cases they will not be on site at the same time - so it's up to you as the 'owner builder' to set-out correctly and advise the various trades what needs to be done.

"Can I assume present day timber flooring and joists and bearers will be the same as used in the original house (1940s) so maybe I can just take my levels from those and existing bricks?"

mmm - no, not a chance that they will be the same. In any case can I suggest that if you aren't having a professional to assist you at least get yourself a copy of one of the Alan Staines books, probably the Owner Builder & Renovator 7th Ed. (from online eg: Building and Renovating Books (http://www.peachinstitute.com/books.html) or at hardware stores etc) and read it all the way through as a first step then keep it handy. It is pretty clear from your questions that this is a big job for your experience level and it is not one you want to get wrong.

As to your extension - you need to determine where the new finished floor level needs to be (the top of the existing flooring) and transfer that level accurately to the outside of the building and then transfer that level mark top at least two other fixed objects which will not be moved during your construction work. That might be a fence, parts of the existing house or even a tree, or a solid peg or steel post placed into the ground especially as a level peg - this is similar to what Gaza was suggesting with a template (which is good idea for a novice or DIYer - but measure twice, or thrice!) - get this wrong and all your setout will be wrong.

When you have that level mark that is what you will stay working from throughout the construction - down to get levels for the sub-floor and up to determine ceiling lining height (to match existing too) and ceiling/roofing design and placement above that. So for the sub-floor you will need to know the dimensions of the flooring you will actually be using, then the joists and bearers. Common measures would be 19mm or 22mm flooring, 90mm joists (90x45) and 90mm bearers (90x90 or 2x90x45) which means that top of the brick course on the strip footing on which the bearers are sitting - which usually means on piers behind the face bricks) will be down 19mm+90mm+90MM = 199mm from the top of the flooring level.

The top of the strip footing position will be determined by the brick course heights - again measured down from where the finished floor height is to be (to match the existing floor). You therefore need to know what bricks or blocks you will be using and their dimensions - as Gaza said there is a little flexibility available for the bricky to make up levels, but that should be minimised by correctly setting out in the first place.