The Fresh Loaf

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Help with a WFO foundation question

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Sinon's picture
Sinon

Help with a WFO foundation question

Rookie builder question.


I am starting to plan out the build of my WFO and have a construction question for the more knowledgeable builder members:


Off the back of the house we have a wooden deck, which steps down to a brick paver patio, which steps down to the grass and my wife's (foreman's) flower beds. The rear of the property has a gentle slope to it, so when we put in the patio, we built up to 'level' with an aggregate and crushed stone base. Unfortunately, the 'approved' (foreman's, not municipality's) position for the WFO would currently leave it cantilevered (say half on / half off) the patio with a 1.5 foot drop down below it. I see a number of alternatives and have not a clue as to which is the better (easier, sounder, aesthetically pleasing) approach:


Approach 1


Extend the patio under the WFO with crush, aggregate and pavers so that the area is homogeneous, and float the WFO's concrete pad on top of the pavers. (Is floating a pad on pavers sound / stable?)


Approach 2


Rip out the full footprint of the WFO from the existing patio, pour the pad and build up with concrete block. (Feels like a good way to screw up the patio and my wedded bliss in pursuit of a WFO.)


Approach 3


Pour a pad off the edge of the patio for the overhang, build up with concrete block to patio level and then pour a pad that floats on the patio pavers and concrete block build up.


Approach 4


The right approach which is not even a twinkle in my eye.


Thanks in advance,


Sinon


PS...I'll create a blog so that all can laugh along with my foibles as this build out goes along.

Missionsman's picture
Missionsman

What style of oven are you going to build?  What part of the country are you building?  Depending upon what style of oven you are building will dictate the foundation and then this will be affected by the frost line where you live.


Mark

PMcCool's picture
PMcCool

If you could supply a photo or two of your intended WFO location, that would be helpful.  I'm not quite sure I have the correct picture in my head of your current patio construction.  Since you don't mention any type of retaining structure (timbers, concrete wall, brick, concrete block, etc.) around the patio, it sounds as though the patio is bounded by a slope of aggregate and crushed stone that runs down to the grass below.  Is that correct?


Other useful bits of information: soil type and climate conditions.  Is your soil stony, silty, sandy, clayey, or some combination of those?  Is there rock within a foot or two of the surface?  How cold do your winters get?  Cold enough that there is appreciable (more than a foot) of frost penetration?  Keep in mind that (if this an issue at all) frost will penetrate more deeply below your patio surface than it will below your turf.


Without knowing any of the above, Approach 2 is your best bet.  Even after knowing all of the above, Approach 2 is probably still your best bet.  Approach 1 leaves you vulnerable to future settlement of your WFO's foundation (even worse, settlement of only part of the foundation).  You will find it very difficult to get the crushed rock and aggregate compacted enough to prevent settling underneath the very significant weight of your WFO.  After investing the money and energy to build it, you don't want to see it tilting or cracking.  Approach 3 also leaves you vulnerable to differential settlement.


Here's an idea for an Approach 4: build the entire oven just off the edge of your patio.  You will probably have to take up 3 or 4 rows of pavers from the patio nearest the oven location to do your foundation excavation, but those can be put back easily (I'm assuming that they are sand-bedded).  Benefit 1: you get to build a one-piece, solid concrete foundation to whatever depth is necessary for your local soil and climate conditions.  Benefit 2: with the foundation built up to the level of the patio, your oven will look like a natural extension of the patio, particularly if you use a similar-color brick for the oven exterior.  Benefit 3: you don't lose any patio space.  Just backfill the excavation and relay the pavers that you had to take up to make room for working on the oven and you are back in business.  If you have the budget and the aesthetic preference, your oven's foundation can include a brick ledge so that you can install a brick cladding all the way from the sod to the top of the chimney.  About the only exposed concrete would be a bit of the footer at the back of the oven.  Even that can be hidden if the flower beds are extended to wrap around the oven structure.  If you are really enthusiastic, you can even design it so that you have the WFO on one side and a grill on the other, all integrated in a single structure.  But, hey, it's your money and your project.


Best of luck!  I look forward to your progress reports.


Paul

Faith in Virginia's picture
Faith in Virginia

As a professional builder I will say that Paul is absolutely correct.  I believe that you are the one from the Chicago area.  So yes use a full footer below the frost line.


Good luck and see you at the KA class. 

Sinon's picture
Sinon

Faith is correct, I am in the Chicagoland area. 


Looks like it is going to be the rip out option unless you see something in the pics that leads you to a different recommendation. 


View from the deck stairs looking towards the oven placement...to the left of the fire pit.



View looking back at the deck from the proposed oven site. I see the oven kitty cornered so that when standing on the deck stairs, you are looking right at the hearth.



 


Patio has interlocking wall perimeter and unfortunately, space remaining between the patio and the flower beds will not permit the 32 X 36 Alan Scott Bread Builders type oven to be just 'bolted' on to the patio...at least I don't think it will... have to check new dimensions tomorrow. Was originally looking to get away without using footers and just do the pad with insulation described by Mr. Scott. If i go with the footer option, I may have a tighter envelope.


What is the recommended brick ledge size for bricks that are going to be tied directly to cinder block? 



 


Patio Base



 


Mark, Paul, Faith...thanks again for for helping out a guy who knows just enough to be dangerous....


Sinon


PS See you at the KA class Faith...

PMcCool's picture
PMcCool

Sinon,


If you wish to orient the WFO on a diagonal, relative to the axes of the patio, be sure to site it far enough away from the projecting flower bed (to the left, if you are standing on the patio looking at the WFO) that the raised edge of the flower bed isn't a trip hazard.


After seeing the layout, you may wish (although it will require more work and expense) to surround the WFO with patio, after it is constructed.  That would entail shifting the face of the patio that is left of the flower bed outward some amount to reach the back of the WFO, filling in the area, then laying new pavers to cover the additional patio surface.  You know the dimensions of the patio and the WFO.  You might find it helpful to chalk the outline of the WFO in your intended location, then see what that would mean in terms of the patio.  At a bare minimum you will need more patio surface in front and to the right of the WFO to close the gap left by the diagonal orientation of the WFO.


Simpler and cheaper still, build the WFO immediately off the edge of the patio, aligned perpendicular to the patio face.  You could leave the patio untouched if you can avoid undermining the retaining wall.  Given the loose material under the retaining wall blocks, that could be dicey.  You might still need to take out a section of the patio wall and floor immediately in front of the oven while you buld its foundation, then relay the patio components in their original position after the oven foundation is backfilled.


A brick ledge is just a part of the foundation (a concrete shelf) that sticks out far enough from the vertical face of the foundation to rest the bricks on.  If you use 4-inch bricks, you'll need a 4-inch wide brick ledge.  Talk to a bricklayer friend for more specific details.


Your WFO should be a great addition to an already lovely home.


Paul

Faith in Virginia's picture
Faith in Virginia

My thought would be to check the footer size of that square guarden off the edge of the deck then steal that space and put the oven in that location.  If you removed the dirt in that box and poured a good footer in that hole you could build your stand inside that existing stone work.  Then you could match that stone up to the bottom of the oven  and incorporate it into the platform for the oven. Then to make the forman happy relocate that guarden to the left and wrap that corner over towards the walk way.  That would be a nice place to plant some fresh herbs that you could pick fresh and put on pizza.  If the footer is not sufficient there are ways to make it so with out any great expense. It's helpfull that there is a footer under that wall. The people that did that work looks like they did a great job.