Decking sub frames

Discussion in 'Carpenters' Talk' started by Decking DIYer, Aug 10, 2010.

  1. Decking DIYer

    Decking DIYer New Member

    I wondered if anyone might be able help please...

    I am putting in a raised deck (just above the level of the earth) in my garden and have put in very good posts all lined up etc and the foundations are very strong in concrete. I am embarking of looking at the required timber for the beams and joist which I would like to do with 4 by 2 pine pressure treated material (as I dont have space for 6 by 2 given levels of fences in my garden)

    I have looked all over the internet to see what size of timber and in general terms the subframe is made of 6 by 2 or greater.

    Question is, if I reduce the gaps between the joists and include lots of noggins would using 4 by 2 be acceptable to using much larger wood. I also plan on strengthening the frame with a batterboard and also onto a wall which the frame will go over.

    any help would be sincerely appreciated.


  2. saddle joint

    saddle joint New Member

    A good well made question. Unfortunately you neglect to state the one piece of information that's necessary to answer your question and it is, what's the span?

    Generally speaking 100mmx50mm needs supporting at about 1.5-2m if the joists are on 400mm centres. The grade of wood has to be taken into account. c16-24 is stronger and more durable than other non-graded types. Always err on the side of safety.

    What are the dimensions of the decking that you propose using? How far apart are the boards going to be placed?

    My final piece of advice, look around for a local carpenter and ask for "an all in price." You'll be amazed at how cheap it works out getting a skilled man in. He'll organise everything for you. He's got access to tools, knowledge and finally he'll advise you about finishes and maintenance.
  3. Decking DIYer

    Decking DIYer New Member

    dear saddle joint,

    many thanks for taking the time to respond and this is much appreciated.

    you sound like you know what you are talking about and i am new to this but i am an enthusiastic diyer and have read up quite a lot on this and wanted to try it myself (i had tried on many occasions to get quotes but nobody would provide them when they originally saw what needed to be done in the garden with earth shifting and getting materials through the house etc)

    it has taken a good year and a bit to get posts, ground level and solid in spare time.

    I have an area of approx 3 metres by 6 metres and have errected 12 posts in solid concrete that will have double beams either side of the posts with coach bolts that i was hoping will support a frame of ideally 4 by 2 treated timber. The span between the posts is approx 1.5 metres.

    I had hoped that i could use 4 by 2 throughout...

    I wondered does that help ?

    not sure what you mean by 400mm centres?, does that mean that when i make the frame that the joists should be 400mm apart with noggins or perhaps that i need to put more dreadful posts in ? eeekkk

    any response or help would be much appreciated


  4. Mountain Man

    Mountain Man New Member

    All sounds OK as you've described. You have enough posts in. You get the joist spacing by laying a length of your 4x2 between the joists which are bolted to the posts. Each end or these joists will be supported by the perimeter 4x2s. Tight fitting noggins in-between will make it all rigid. It will finish up looking like a load of ladders laid out, some of which will be bolted to your posts. I've done loads of decks and had no problem using 4x2 cls when a low profile is needed. By the way, as 4x2 cls has a finished size of 44mm, dont use joist hangers for 2 inch timber. They're too big. The hosts of this site do 44mm hangers which I recommend.
  5. Decking DIYer

    Decking DIYer New Member

  6. Mountain Man

    Mountain Man New Member

    No - you want these - item no. 37246.
    You'll have too much slack in the 50mm ones if you use planed timber.
    A pair of tin-snips are handy for trimming off the excess metal.
  7. saddle joint

    saddle joint New Member

    Right you seem to be heading in the right direction. Mountain Man has given you some good advice, act upon it.

    Whenever I use joist hangers or truss clips I like to use screws they are more accurate and less likely to bounce about as you fit them.

    Good luck.
  8. Decking DIYer

    Decking DIYer New Member

  9. Decking DIYer

    Decking DIYer New Member

    sorry based on both of your excellent help i mean ...
  10. Mountain Man

    Mountain Man New Member

    No - they are too slack as well for planed 4x2. In all the decking I've done, I've only used the hangers I previously recommended. If you want to be really neat, where the legs of the hangers wrap over the perimeter timbers, I rout out a couple of mm. so the deck boards will lay flat.
  11. Decking DIYer

    Decking DIYer New Member

    hi i was going to use the truss clips to secure the mainframe to the deck beam as they are at right angles.. i was toying with just using very big screw to secure the frame... but saw trusses and thought this might be a good idea... thanks nige
  12. Decking DIYer

    Decking DIYer New Member

    i think they are also calle dhurricaine clips or twist brackets if you know what i mean ?
  13. Kinger

    Kinger New Member

    Super advice already, but I dont think you have enough posts !! - 15 minimum if i was doing it !! - Good luck !!
  14. Decking DIYer

    Decking DIYer New Member

    hi i was trying to source mini hanger clips (they sell the 50mm ones here i.e. 2inch ones) however i need 44mm ones ie after 4 by 2 is planed...

    i tried who it would appear manufacture the clips (they have 38mm, 44mm 50mm varieties on their website), but they said they dont have any.. bizzare ...

    anyhow any advice would be good... else i will need to use the bigger jiffy hangers and cut with some metal cutters..


  15. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Use 2" ones and pack bottom and one side with cut strip pieces of 6mm ply. Ensure one fixing in each bit of ply.


    Mr. HandyAndy - Really
  16. dunc dunc

    dunc dunc New Member

    As I work alone usually I build a deck in small frames. 4x2 at 400 centres with 4x1 tying the ends together. lengths depends on the space within which they are to be fitted, so it will vary between 6 and 12 foot by 4 foot.whatever is an easily lifted and manouvered frame.

    these are clamped onto 6x2 verticals until i get an overall level and slope using strings and spirit levels. then the feet are concreted into the firm ground below the top soil. easily done one at a time.

    then when its all set i lay out some boards and walk about to see how well it feels. if needed i strut beneath the main frame. then its the noggins.

    this is fine and i have gone as much as 4ft below the deck, bracing with diagonals where needed.
  17. Decking DIYer

    Decking DIYer New Member

    many thanks

    I am going to use 4 x 2 as a ledger board which is going into a breezblock wall... can anyone suggest the correct fixings from screwfix that would provide sufficient strength for this please ...

    with a M10 x 75mm (does this mean that you need a number 10 drill bit? and then the length of the thread is 75mm long ?

    any help would be appreciated.


  18. Mountain Man

    Mountain Man New Member

    Crikey - not finished yet?
    Those posts will need pruning come autumn.

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