Decking Questions

[Rabmac1]

I have never built decking before so want to make sure I am doing it right. So would really appreciate it if you pros could answer a few questions.

The first question is related to building the frame for a level decking sitting on a slope. What do I rest the joist on at the top of the slope and do you just put a post at the bottom of the slope and fasten the joist to it as I have drawn below?

The next question is do I need to use bat joist hangers or what are the benefits of using them?

Thanks

 

[AronSearle]

Make the decking surface higher, so that you can screw a wall plate/joist to the wall with packers, and have it clear from the ground.

 

[Rabmac1]

Do you have a link to a website that stocks the wall plates so I know what I am looking for.

Do you also have a picture of how things would look when you do this so I know what I am trying to achieve.

Thanks

 

[foxhole]

Make sure you have room below the dpc at the wall.

 

[Rabmac1]

What size of gap would be adequate?

 

[AronSearle]

Wall plate = Joist screwed to wall on packers for decking joists to hang on.

Gap below the DPC = Ideally 150mm, but it is unlikely you will have this, whether it actually maters is a big debate and will depend on your house construction.

Do you have a book on this, you can buy them for a few pounds and your questions suggest a lack of knowledge on the basics.

 

[Rabmac1]

Yeah this is all new to me Aron but want to learn. When you say packers, is that just another piece of wood placed between the house and the joist to make sure the joist is not touching the building? For the record I intend on putting flashing tape over the top and ends of each joist to make sure it lasts longer.

My house is 1920s built and from what I can tell it has 2 double layers of brick separated by a cavity.

The DPC is in the cellar and consists of a thick layer of tar like substance poured over the ground.

 

[AronSearle]

You will get mixed answers about installing decking just below or above the level of the DPC, because I am not aware of any definitife information that says this can actually cause a problem, especially if the cavity is uninsulated, you will have to decide the level of risk yourself, also consider prevailing conditions.

Plastic packers or another inert material would be best.

Flashing tape is unecessary if the joists are properly treated, if they are not, then it won't save them anyway.

 

[Rabmac1]

Thanks for the help everyone, really appreciated.

 

[Harbourwoodwork]

Alternatively you could put supports in the ground away from the house and cantilever over and save yourself a lot of problems.

 

[Rabmac1]

This is kind of what I was intending to do:

http://www.jwkhomeinspections.com/system/files/userfiles/Deck_Const_Image.jpg

 

[Harbourwoodwork]

We are going in circles here.

 

[Rabmac1]

What do you mean when you say cantilever over?

Is that how I attach the wall hangers to my house?

 

[Harbourwoodwork]

I am suggesting,the same construction on the house side as the front edge
Not attaching to the house at all.

 

[GuyWest]

Not sure if this is going to end up being helpful at all, but I follow this guys blog and whilst he is not a DIY fan exactly, amongst all his complaining he does occasionally come out with some good stuff.

He talked in his last post about putting up some decking, so he will probably be posting images of the decking he has recently put up, as well as how he did it and what he used.

Hopefully it will help you out: http://thediyunenthusiast.blogspot.co.uk/