correct method to level floor joists in loft

[johnstone]

would appreciate any opinions regarding around 20 floor joists which are running off level around 3 inches going across the joists from one end of the loft to the other theres a 70mm run and difference in height of nearly 3 inches.they run off in both directions across and in length.more so across from one joist to the next and so on. have had a few opinions from various joiners which they all have different ways and methods of levelling these joists.some would go onto the sides of the existing 6x2 inch joists with new timber and others would go in the opposite direction on the top of the joists and across them with new timber.thought cutting all the angles with new wood on top of the joists following in their direction would be the best process of levelling but not many joiners seem keen on that way as apparently theres a lot of angled cuts involved and some joists are slightly bevelled. need it levelled in order to lay chipboard flooring to use as storage space but would like it levelled correctly if it maybe gets converted in the future.any knowledgeble opinions would be truly appreciated. thanks

 

[Deleted member 174758]

As in many joinery solutions there isn't one single "correct" solution. The "best" practical solution is the one which takes least time, manpower and materials. Sight unseen it's not always easy to call, but I'd probabaly favour new timbers across the tops of the existing timbers at right angles, packed off and screwed together as making the least work

 

[johnstone]

as in many joinery solutioms there isn't one single "correct" solution. The "best" practical solution is the one which takes keast time, manpower and materials. Sight unseen it's not always easy to call, but I'd probabaly favour new timbers across the tops of the existing timbers at right angles, packed off and screwed together as making the least work

thanks for your opinion with regards to that do you mean going on top of the exsisting joists following in their direction with new timber on top,cut at all the angles to level which would take a lot of skilled cuts around 100 metres over 20x5metres joists and would it be possible to get it levelled this way which would take more time to complete or the would you advise the other method with going on top of the joists with 3x2 in the opposite direction from the joists with a new floating floor which we have been quoted for all methods including the 3rd option was going on the sides of the joists with new timber in order to level.all methods have there benefits and flaws just want to know what is the best and correct way because we dont want to ever have to level it again in order for it to take the weight of a conversion in the future if it can be done correctly now could save a lot of hassle in the future. the house is a 1930s semi detached and the problem may have been caused by subsidance over 80 years. the loft is 11metres in length by 5 metre in width with the joists runnin across the 5metres width of the loft. over the 11metres in length there is around 20 joists running across the 5metres width of the loft.one end of the length of the loft is the highest point and all 20 joists are basically taking a step down from one end of the loft to the other which results in a 70 mm run of the level and difference in height.the joists are also running off in their diection across the 5metres width of the loft aswell although not quite as bad as from one to another.thanks again for any advice

 

[Deleted member 174758]

thanks for your opinion with regards to that do you mean going on top of the exsisting joists following in their direction with new timber on top

No, at right angles, notched or ripped as required (the timber yard should be able to do the rips). I feel that trying to cut tapers is somewhat of a fool's errand (i.e. extremely time consuming) unless you absolutely need the maximum headroom. When clad I reckon this floor will have more rigidity than one where you've added parallel timbers to the sides of the existing joists, especially if you can get 5 metre timbers up there to do the span in one length. If you have a 70mm drop then the parallels will need to be of much taller section, too - about 120mm at one end, so potentially more costly. Common problem in this part of the world where we have a lot of steep sided valleys