Building a back porch - advice needed

heathicus · Post by **heathicus** » Tue Jul 20, 2010 10:34 am

This is more carpentry than woodworking, but I thought I would ask here anyway...

We're moving soon and one of the first things I need to do is build a back porch. I've never built a deck/porch before, so I read a few "tutorial" type pages online. But those pages just don't seem to answer many of my questions. So I was hoping you guys could help.

My plan is to use 4"x4" support posts, concreted in the ground. Those tied together with a 2"x6" support beam. On top of that would be 2"x6" floor joists. On top of that would be 3/4" tongue & groove plywood. It will also be screened in with a roof. Since there's just not room in the house, one end of the porch will hold our deep freeze and extra refrigerator. Overall size will be about 20' long by 10' deep. My questions...

How far apart should the support posts be? Should I add extra support beams under the fridge & freezer?

I plan on spacing the floor joists on 12" centers under the fridge & freezer. Is that adequate? Is 16" centers acceptable for the rest of the porch?

I don't need the porch to last a lifetime. A five year lifespan is all I'm expecting from it. That said, should I beef up the support posts or beams and go to 6"x6" posts or 2"x10" beams?

beeg · Post by **beeg** » Tue Jul 20, 2010 10:48 am

I think I'd go with the 6X6 posts, and remember to dig the hole 1 foot deep for every 2 foot in height.

tom_k/mo · Post by **tom_k/mo** » Tue Jul 20, 2010 11:01 am

Heath, I don't know that I'd set the posts in Concrete. They make a metal bracket that you can set in concrete or mount to a concrete footing that a 4x4 would set into, and it holds the bottom of the post just off the grade. This helps keep the bottom of the post from rotting. Kinda like this...

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Ed in Tampa · Post by **Ed in Tampa** » Tue Jul 20, 2010 11:09 am

heathicus wrote:This is more carpentry than woodworking, but I thought I would ask here anyway...

We're moving soon and one of the first things I need to do is build a back porch. I've never built a deck/porch before, so I read a few "tutorial" type pages online. But those pages just don't seem to answer many of my questions. So I was hoping you guys could help.

My plan is to use 4"x4" support posts, concreted in the ground. Those tied together with a 2"x6" support beam. On top of that would be 2"x6" floor joists. On top of that would be 3/4" tongue & groove plywood. It will also be screened in with a roof. Since there's just not room in the house, one end of the porch will hold our deep freeze and extra refrigerator. Overall size will be about 20' long by 10' deep. My questions...

How far apart should the support posts be? Should I add extra support beams under the fridge & freezer?

I plan on spacing the floor joists on 12" centers under the fridge & freezer. Is that adequate? Is 16" centers acceptable for the rest of the porch?

I don't need the porch to last a lifetime. A five year lifespan is all I'm expecting from it. That said, should I beef up the support posts or beams and go to 6"x6" posts or 2"x10" beams?

I think the 4x4 spaced 5 feet on the 10ft side and 5 on the 20. I would used 2x12 doubled around the outside and 2x10 or 2x12 16 on center for everything else. It might be cheaper than 2x6 on 12" centers.

I would build it to last longer than five years. Why did you pick that? If in 5 years you are going to tear down and rebuild I would rethnk my plan. It is always far more expensive to build then tear down and build something else. Lay the foundation now for whatever is going to be there after the 5 years.

heathicus · Post by **heathicus** » Tue Jul 20, 2010 12:51 pm

tom_k/mo wrote:Heath, I don't know that I'd set the posts in Concrete. They make a metal bracket that you can set in concrete or mount to a concrete footing that a 4x4 would set into, and it holds the bottom of the post just off the grade. This helps keep the bottom of the post from rotting.

I've seen these, and I've been thinking about it. It could also save from having to buy so many 4x4 (or 6x6?) posts. But putting the posts in the concrete has always been standard practice around here. But I'm going to consider doing it like this, this time.

Ed in Tampa wrote:I think the 4x4 spaced 5 feet on the 10ft side and 5 on the 20.

5ft in each direction? Or was both direction being 5ft a typo?

Ed in Tampa wrote:I would used 2x12 doubled around the outside and 2x10 or 2x12 16 on center for everything else. It might be cheaper than 2x6 on 12" centers.

Do you mean for the support beams or the floor joists?

Ed in Tampa wrote:I would build it to last longer than five years. Why did you pick that? If in 5 years you are going to tear down and rebuild I would rethnk my plan. It is always far more expensive to build then tear down and build something else. Lay the foundation now for whatever is going to be there after the 5 years.

Well, since you asked... My plan is for nothing to be there (including me) after 5 years. Long story short, we're moving out of town to a mobile home we own (purchased new after we were married, thinking it was a good idea - we've been renting it out to my bro-in-law the last several years). This is part of our 5-year plan to take control of our finances, reduce expenses, pay off our debt, and save to build a house on my family land. So while we need the porch, I also don't want to sink a lot of money into something that's going to last forever when I only need it for a few years.

JPG · Post by **JPG** » Tue Jul 20, 2010 1:06 pm

I concur with Ed re the 5 yr lifespan. How cum

I also concur with Ed re the 5' post separation.

I concur on doubling the supports around the outer sides.

Beyond that I do not!

At this point an opinion is being distributed (not researched).

Me thinks 6x6 posts on the corners and 4x4 posts are adequate. I am suggesting a row of posts in the center of the 10' span(3 4x4 5' separation and a doubled 4x4 on each end [reason below])

Me thinks using a plynth(sp?) on a flat topped foundation (pylon buried or poured concrete). This reduces the total length of posts needed, and eliminates the sawing in half a decade.

The support members(those resting on the posts) could be purchased in 10' lengths to minimize waste.

The support members can be set on a shoulder cutout on the post. A single 1 1/2" cut out on the center of the 'center' posts, and a 1" deep shoulder cut on the sides of the outer 4x4 posts, and a full 1 1/2" shoulder cut on the outside corner of the 6x6. This leaves only a small 1 1/2 x 1 1/2" shoulder available for the inner two support members. Ya need to get creative there!

The 'extra' 4x4 at each end of the center posts is to provide support for the outer end of the center support member(the 6x6 supports the outer pair).

Now I think Ed's suggested dimensions for the support members are over kill (I say this not knowing how far off the ground this structure be). I be assuming it is not too far.
I think 2x8 on 5' supports are adequate(doubled on the outsides).[Support members] Sorry I could not think of a better name]

I think 2x6 on 5' supports at 16" centers is more than adequate. I do not think that would require extra 'refrigeration' support.(Joists)

I would use pressure treated lumber for everything.

That's my view! Please feel free to shoot holes in the 'scheme'.!

terrydowning · Post by **terrydowning** » Tue Jul 20, 2010 1:42 pm

Check with your local permitting office. They usually have Building Guidelines of some sort that will walk you through the process including minimum required engineering and permitting process.

I strongly recommend pulling a permit and having it inspected by your local building authority as it it is a porch permanently attached to the house.

I know here in CA failure to pull the correct permits can result in some serious fines, plus the building office has everything you need to know at the ready.

heathicus wrote:This is more carpentry than woodworking, but I thought I would ask here anyway...

We're moving soon and one of the first things I need to do is build a back
porch. I've never built a deck/porch before, so I read a few "tutorial" type pages online. But those pages just don't seem to answer many of my questions. So I was hoping you guys could help.

My plan is to use 4"x4" support posts, concreted in the ground. Those tied together with a 2"x6" support beam. On top of that would be 2"x6" floor joists. On top of that would be 3/4" tongue & groove plywood. It will also be screened in with a roof. Since there's just not room in the house, one end of the porch will hold our deep freeze and extra refrigerator. Overall size will be about 20' long by 10' deep. My questions...

How far apart should the support posts be? Should I add extra support beams under the fridge & freezer?

I plan on spacing the floor joists on 12" centers under the fridge & freezer. Is that adequate? Is 16" centers acceptable for the rest of the porch?

I don't need the porch to last a lifetime. A five year lifespan is all I'm expecting from it. That said, should I beef up the support posts or beams and go to 6"x6" posts or 2"x10" beams?

billmeyer · Post by **billmeyer** » Tue Jul 20, 2010 2:30 pm

You should go by your local code. Having said that, if you truly want it to only have a life span of 5 years, you do not have to go that beefy. I have a front porch that has lasted for 22 years that is covered but open on 3 sides. It has concrete block supports on bare ground, single 2x6 around the perimeter, and 2x6 joists spaced 24" coming straight off the ledger board to the perimeter with no under pinning. It was built with used lumber, not pressure treated and is still in perfect shape. Having said that, I would not build it that way, but it works.

I would use 4x4 posts go 2x8 perimeter, and 2x6 floor joists spaced on 16" centers. I would add cross bracing under the end where your freezer will be. 5 years does go fast, so make sure what you are wanting. Now I am supposing that the roof is just a porch roof and not supporting anything else, or I would beef it up more on the end. I would also use pressure treated lumber as suggested before.

Good luck.

Bill

heathicus · Post by **heathicus** » Tue Jul 20, 2010 2:53 pm

Thanks for the suggestions, everyone! I'll try to throw something together in Sketchup to make sure I'm wrapping my brain around everything correctly.

As far as permits and codes... this is very rural Louisiana. For example, where I'm moving, law enforcement consists of a single part-time constable. If you're building a house, permits are required. But they don't care about a porch. I can't even find any evidence that there is a local building code. Just statewide codes.

JPG · Post by **JPG** » Tue Jul 20, 2010 3:24 pm

heathicus wrote:Thanks for the suggestions, everyone! I'll try to throw something together in Sketchup to make sure I'm wrapping my brain around everything correctly.

As far as permits and codes... this is very rural Louisiana. For example, where I'm moving, law enforcement consists of a single part-time constable. If you're building a house, permits are required. But they don't care about a porch. I can't even find any evidence that there is a local building code. Just statewide codes.

So YA want the State goons to pounce on ya?:D