how much fall should deck have away from house?

Sorry, no one seemed to look at my latest reply on Attaching ledger and since the question is new topic I started new post.

The slab is front of house and continues 12' past the left side of house. If you were standing in front of the house looking at this slab, you would see the entire slab is sloped away from house-meaning as it gets closer to you it is lower. but the end sticking out past the house on left has no fall to the LEFT away from house. This is where I will build the deck. I guess I should have had the concrete guys slope the part of slab that is sticking to left of house-slope it down to the left so that when I put deck on and slope it away from house that they would line up. It is important to note that this deck will have roof on it, so maybe I don't really need to slope it at all? If I do slope it, what is the best way to mate it to the slab that is level? If I start at ledger side and put it so deck is even with slab and slope deck down, I will end up with a little toe stubber at far end of deck with deck being lower than slab.

 

First off the concrete guys should have told you that left slab needs sloped unless you said you wanted the end level.

Can you start the ledger board up higher to get rid of the toe stubber. If so don;t understand the problem here. the ledger going around the house will be the same. So one slab slopes and the return slab doesn't Build deck level. open decks don't need a slope. Water goes through the plank slots.

PS. All concrete should have a min of 1/4 per foot fall.

 

Another opinion. All decks should slope away from the house. The water that lands on the boards will run back to the ledger before it is dispersed. Only the water that falls near the cracks will fall through. But is it is moot point in your case if you plan on roofing over it. Will you be enclosing it now or later?
Just to clarify, you can't place your supports for the deck on the concrete. You will need to cut the concrete and pour appropriate footings according to local code.

 

here is photo. The entire slab is sloped away from house, down toward where picture was taken, which is fine for area in front of the house, but the area that is to left of house should basically have an angle on the slopes so that part of it slopes the same as rest of slab and the other part slopes down to left to match what the slope of the deck would have been. But can't change that now.



I don't understand about raising ledger? If I do that, then I will have toe stubber at that location. Since going to be covered, do I just put top of ledger 5/4" below the top of slab (5/4" being the height of decking) so that deck and slab are even? and don't worry about fall. I guess I could keep ledger at that height, plan for fall in deck, and then transition the decking where it meets slab by some kind of shimming so that there is gradual slope from the slab to the rest of deck. how much fall should deck have? It will be 12' out from house on left. 1/8"/foot or 1 1/2" for the 12'? then I would have to transition that 1 1/2" out enough so that it isn't trip hazard as it would not be identified as a "ramp"

no support for deck on slab was planned. although this slab does have 30" frost footing as it will be carrying the roof load of the porch roof in front of house. So I would think I could use it for support if I wanted?

 

hammer rash. I don't see a door there yet restricting you on ledger height.

Maybe we aren't on the same page hear. Is this deck actually laying down on the Crete? Give some better details here please so this middle age G.C. can help you. I'm looking at the Crete as basically dirt unless its supposed to be the actual floor for the addition ?? The unsloped Crete tells me there wasn't proper work done and nobody caught it.

Is that flat are supposed to be a parking area and that changed?

I also see 2 b clean crushed stone there. Was that left over from the slab pour? That dirt area looks bit to high or all of the Crete including the pad sloped away from the house too low.

In a nut shell standing from the picture angle shoot the far left pad and level from there. snap/pencil line on house. Thats level. So raising that line will give some slight slope and then do mini post elevate the deck accordingly. now if I'm off base here let me know. Give better details on what lumber you are using in dimensions and is all the Crete getting decking over it?

If you are planning on just laying down 5/4 grids and the 5/4 on that for a floor this is also bad construction. for drainage under the floor not to mention possible mold starting, and the treated lumber will rot due to wet Crete especially in that flat area. So please get back to explain more thanks!!

 

no, the deck is not going to be sitting on slab. but the deck will be on left of house and will meet the slab in front. The slab IS sloped-water running down that downspout does fall off the front of the slab. The deck is going on the left, and will wrap around the back, which is where the door will be. So there is some restriction on height. If I made the deck so it is same height as the slab, I will end up with a 4 1/2" step into my house. Inspector was fine with that.

You are right, I do have grade issue in front. What I was thinking was putting a retaining wall on the left edge of concrete and extend it around the left front corner to about the end of the first "groove" in the pad, which is where the end of house is located. The concrete has adequate footer for this as I did plan it out. Just forgot to have them slope the leftmost section of slab down to left, instead of down to front.

you are correct that is 2B stone. It was from pour and will be using it in driveway also.

will be using 2x8 for ledger and joists. Undecided about surface. Looking at composites. Trex samples are 1 1/8" , EverGrain and AZEK are 1". I will decide which I am using first, then plan ledger accordingly.

If I snapped a line even with slab at left front of house and then raise that up, I will have toe stubber as you walk from slab to deck.

 

Slope the deck to match the slab that you are attaching it to and there will be no "toe-stubbers'.

 

so make the deck flat without any fall away from house? That is what it will be if I match slab.

 

Your existing slab has a slope. To attach your deck to it you will either have to build the same slope into the deck so that it is flush with the top of the slab, OR build the deck level but have it one step up (or down) from the slab. If you add the step to adjust for the slope in the slab, the RISE of the step will have a slight variation from one end to the other -- whatever the slope of the slab is -- but that won't be noticable nor will it be a 'toe-stubber'.

 

sorry its been a while. I think you are confused lefty. The slab does NOT have any slope in the direction that the deck joists will be running. see above photo. the entire slab slopes down in direction of where photo was taken from. water falling on that portion of slab to the left of the house will not run off the slab to the left, it will run off the front of the slab. I have another problem, but since not related I will start new thread.

 

I'm not confused -- your slab slopes to the left in the photo, and your joists will be perpendicular to that slab (running out to where the photo was taken from). If you make the deck level, you'll have a 'toe-stubber' at one end or the other where the deck and the slab come together.

So, you have two choices. You can build the deck with a slope that matches the slope of the slab, which eliminates the 'toe-stubber', or you can raise or lower the deck one step and make it level, which means the rise of the step at one end will be slightly different than the rise of the step at the other. But nobody is going to stub their toe on THAT!! It's a gradual change.

 

NO, there is no slope to the LEFT. If I were to put a level running left to right in the photo, it would show that the slab is LEVEL. But if I put the level with one end at house and the other pointing to where to photo was taken from, it would show fall away from house. All three areas of the new slab are that way. And the left of the house is where my ledger board is going to attach with the joists running left to right as seen in the photo. So if I put joists even with slab along their entire course, the deck will be level. Since this is going to be covered and 12' wide, I guess this will have to be OK as no water is going to be anywhere near ledger. I suppose I should have caught this when they were pouring so I could have had them slope to the left.

 

OK -- it's been a while, but now I see what you are looking at.

You don't want to build the deck "level" as that will create a 'toe-stubber'. Build it to match the 2 slabs that you will be attaching it to. In one direction, that will be "level", and in the other it will have the same slope as the slab.

Don't concern yourself with "level" -- keep it flush with the slabs involved.

 

hammerrash. From finish floor of the house to finish floor of the concrete slab how many inches is this??

Is the problem here you are trying to just lay down some boards on the slab and 5/4 decking floor on that??

I think the answerers here are all over the place because the first general description is hard to get. It is for me and I'm a builder or maybe I'm slow....

Its an oddity of pouring a angle slab and a level slab or for that matter building any deck over a new slab period, unless the deck is a story above the crete.

 

I guess it is hard for me to explain any more. the pic shows the front of the house. you see how the slab extends past the house (by 12')? it was done that way because I am going to build a 12' wide deck on the left side of the house. you will walk from the concrete directly onto the deck without any step and then you will be able to walk all the way to the back of the house. This will all be covered-notice on the far right of the pic that there is a roof over porch from old house. This will be extended all the way to left edge of slab and then will make a 90 and go all the way to the back of the house. So the ledger that I am describing is attached to the left of the house. the joists will run left to right in the photo. so I guess they should fall away from house, meaning the leftmost portion of joist being lower than the side attached to ledger and thus house. but the slab does not have any slope in this direction. anything falling on slab will fall toward the vantage point of photographer. it will not fall to the left. so if I put ledger so that the part of deck near house is even with the slab and then put some fall in the joists, the leftmost portion of deck will be below the slab.

5 1/4" from finish floor height to slab. I think i said 4 1/2" before but that is using subfloor. forgot to add 3/4" for hardwood inside.

 

OK I think I got this part. The pic is the front of the house. ( didn't see a front door and saw a small roof to there right) Thought it was the back showing in pic

So form the level pad ( on the left in pic) heading toward the back small garage theres going to be a deck for the wrap around porch roof. YES??


Heres the other confusion. When you say the "left side of the house" I assumed it was the left side of the house in the pic. Not a "RETURN" which is the terminology to go down the left back side of the house to that old garage YES???

Think I got it now. The deck flooring coming out from the ledger on that "return" will need to be sloped. And the 12' pad that goes against that first joist "band" will slowly rise above the deck because of sloped deck... YES??

What is the elevation drop off from the level 12' slab to the dirt on side of house the " return"

If this is right do far let me know. If it is I have some solutions here.

 

I think you got it. it is a wrap around porch-shape of L. Actually the more like a C as it will eventually continue around the back and that is where there will be another entrance into house. the roof may not continue in the back of house.

if looking at left elevation view of house, with slab being to the right of house, you have the following:

at far right of house near the slab, the distance from top of slab to the dirt is only about 1'. At the far left of house (the house being 29' deep), the distance from the projected top of slab to the dirt is about 4'.

 

I think whats throwing you for a loop here is how you are perceiving the 12' slab.

To get this in the head right pretend that new 12' Crete level pad is part of an inside corner of a house, and not a slab. Normal for decks and floors.

Starting from where the new 12' level slab is( point of it touching the house) , head/chase down the back side of the house toward the old garage and level that. From that point slope out for the fall you want. Normally 1/4 per lineal ft.

Form that lowest point furtherest away form the house chase a line back up to the level 12' slab where the width of the deck would be. From there starts the other slope. A compound slope. The ledger/finish floor can now be level with the new 12' slab and no toe kicker and still have slope coming off of two points of the deck

Its splitting hairs here all wood decks drain through the cracks unless its a solid floor.

So Do I have this correct in understanding the problem??? and solution?? If not get back...

 

I think you got it, and I got it! So the joist closeest to the slab would be level (like the slab) but as you go back toward old garage, each successive joist would have gradually increasing slope away from house. I guess that it is such a small amount that it isn't noticeable, and since the ground is sloped around there it makes it even harder to perceive that the deck slopes back .

 

Yea is in both heads. This is not that much difference then a L slab or deck wheres there 2 doors, one on each part of the L

The water overall slope is right after the 12 slab to the furtherest outside corner to the old garage. That corner post will dictate the whole compound slope of the deck. You are water shedding from the slab and from the ledger board on the house. Its a bit of a pain for the porch roof post but thats what you are stuck width.

If you are getting a roof above that deck then even better. It WILL drain on the compound slopes. Actually if a windy storm came through on any sloped deck the slope become a moot point. Its the counter flashing where the ledger board is against the house that counts the most here.

Hope this clears it up for you and clear it with the inspector.

Personally I'm not an inspector code worshiper. Too many codes are to general and don't overlap properly. Fought some and won. Codes are good without a doubt. Its the interpretation thats bad.

Ironically one of the best complements I got in the trades was from a City Inspector (City 50,000) He said in front of some other people that I was the best structural contractor in the city. No we don't drink beer together.

 

regarding the flashing. after reading about ACQ and its effect on aluminum, and a previous post, I decided not to use it and instead was going to use the pre-bent vinyl. Using aluminum would require putting water/ice shield roofing paper (paper I found said NOT to use regualar felt paper) and it had to go between ledger and aluminum -pretty pricey and seemed like pain so decided to use vinyl. considered copper, but decided against it- can't remember why.

you don't put anything between the house and the ledger, correct? the flashing directs the water over the ledger and the bottom of the ledger is well below any wood so no water dripping off the ledger is hitting framing-just foundation.

why the pain with the porch roof posts? they are different lengths you mean?

debating now whether to have the joists 12" or 16" OC. I know the steps they suggest 12 for the AZEK. i think the boards will be perpendicular to joists, unless wife decides she wants them diagonal.

 

I believe in counter flashing and flashing. I have been using 0.60 rubber roofing for counter flashing. Look at how well it takes a beating on a roof. With the rubber roofing there is a small can of "Lap Cement" The caulk for it is "SPM" seal.

I like the rubber for a backup. When we put a deck over a roof we have to nail in "sleepers" to attach the deck I cover the sleepers with rubber. It seals well. Look at all the protrusions out of a roof in venting etc. Old vent pipes and mechanicals units need sealed in contact with the roof.


Just the diff in post heights cutting thats all..


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I would go the 12" OC. Just in case at the last minute the Miss's wants it at an angle and you are covered. There is only one chance at this. Call it board insurance...

I almost forgot to mention this. After you set the joist and of course keep the backs up. String line the tops and check for a high backed joist to its sister joist. A high joist is really picked up in composites decks because of its perfect dimensions, it looks more like a poured floor.

Reg PT 5/4 doesn't telegraph it so easily because of the diff in wood plank colors and heavier texture/grain. Just a heads up to you... If you have a couple of high ones power plane them down.

 

Isn't the siding considered counterflashing? so you are saying put the rubber with it overlapping the prebent vinyl flashing. Then put the siding over top of that?

I have attached a pic of the ledger near the concrete. It is only nailed at this point. I left about an 1/8" gap to concrete. the height is such that when I put the Azek on top, it will be at same height as concrete. So how far away from concrete should first joist go? I figured I could put it several inches away so that I have room to the right of it to get bolts that hold the ledger to band board and foundation and then also room to get in a joist hanger. So the deck boards will overhang the joist. What is max amount of overhang I can have with the Azek deck boards.

 

The siding is not a flashing. You need to bend the vinyl flashing into a "Z" shape. Slip one edge up behind the vinyl siding, let the flashing run horizontal across the top of the ledger, and then it bends down the face of the ledger. It is there to keep water from getting both behind the ledger and to keep it off of the top of the ledger.

The Azek can overhang the back side of the ledger 1".

I would use redheads to attach the first joist directly to the side of the concrete, 1" down from the top so that the Azek is then flush with the top of the concrete. I would put a "U" shaped flashing on top of that joist.

If you leave the end of the Azek overhang the joist by several inches, the end of the deck boards WILL curl down.

 

I know about the "Z" flashing. I already have it -prebent vinyl. I thought that the siding was considered counterflashing (not flashing). it goes overtop of the flashing and extends up higher on wall than the flashing.

OK, so I should attach the first joist to the slab-flashing it first. That is what I needed to know. I wasn't sure if I could put it about 2" away so that I would have room to nail a hanger onto the ledger. If attaching to the concrete, I don't need hanger. May just put an "L" bracket between it and the ledger.

 

You can put an "L" bracket where the ldger and joist meet, but if both are properly attached, it really isn't needed.

I suggest using a flat waher to space the joist off of the concrete so you will have a small gap to slip the "U" flashing between the joist and the concrete. Another option would be to use Grace Vycor on the joist, which you could stick on just before you slide the joist onto the redheads.

The joist tops are the part of a deck that are most suseptible to water damage. They collect debris and that debris holds water/moisture on them. I always cover all joist tops with Vycor before installing the decking.