SNEEDLE PROPS LTD
GUIDANCE AND HEALTH & SAFETY
Before you commence any form of Needling you should be a competent builder and have a good knowledge in this field.
If you have any doubts whatsoever about unusual loads and or the condition of the masonry or timber you should seek professional advice from a structural engineer.
As with any needling job you must determine which way the ceiling joists run. If they run perpendicular to the position of the new opening planks and Acrows will be needed to support the floor above.
Firstly, ascertain the overall height of the steel RSJ to be put in to the opening as this is crucial to the height of your top holes to be drilled for the Sneedle Props. The top of the top holes should be at least 180mm clear of the top of the new steel beam's location, to allow plenty of room to lay a course of bricks and to dry-pack later on.
When you know your exact location of where the steel should go, mark out on the wall where this is going to be with chalk. Then above this, mark out your top holes, using the length of the new steel in millimeters, divide this figure by 750mm, for example 3000mm long steel divided by 750mm = 4 so at 750mm centers this will give you four Sneedle Props at 750mm centers and a starting point of 375mm either end, the 375mm at each end is important as there will be a bit of knocking around in these areas when making room for the new steel, also you don’t want to have one of the lower members of a Sneedle prop knocked through where the wall is staying!
Now that you have marked your top holes these can be drilled, so using a pilot drill i.e. 10mm masonry bit drill through the outer skin brick or block work then change to a 127mm core drill and drill all the way through this outer skin, remove any debris Now that you have access you can measure the cavity thickness; this should be done on each hole as they may vary slightly.
For the internal skin this could be brickwork or blockwork and of varying thickness generally 100mm/4 inches but don’t assume, some blockwork can be 3inch 5inch or even 6inches thick. This can be determined by measuring a wall where a window or door is located by measuring the overall and subtracting the outer skin, cavity and wall covering.
Once you have confirmed the thickness of the internal brick or blockwork measure the depth of the external brickwork + the cavity, then add the measurement for two thirds of the thickness of the internal block work, remembering to have allowed for the internal plaster finishing and transfer this total measurement on to your core drill with insulating tape Now you start to core drill the internal blockwork from outside as soon as the core drill has created the 127mm circle about 15mm deep, remove the center guide bit as you don’t want this to go in to the rooms upstairs!! Then continue until you reach your taped mark against the outer face of the brick work. We suggest that you do this for all the top holes before changing the core bit to a 50mm core drill (just to save you time) Once all the holes have been core drilled to the predetermined depth, set up the 50mm core drill to the same depth and precisely core three overlapping holes within the 127mm hole remembering to remove the core drill center guide drill bit again, as not to drill all the way through in to the upstairs!!
The segments will now break out easily using a long chisel and hammer leaving a clean socket The next stage is to mark vertically down the wall, the center for the lower members of the Sneedle Props and break through the wall at these points ensuring there is enough room for the lower member of the Sneedles to fit through easily. If there are doors or windows in the way these must be removed first! Ensure that you have a level solid base for all of the size 0 props to sit and sole plates for inside and outside ideally a plank so all the internal size 0’s sit on one plank and all the external size 0’s on another.
NB, we suggest now that band stands are put in place to hold your new steel up and out of the way dependent on the weight of the steel this may need to be supported AS WELL AS by genie or equivalent lifter. Carefully put your steel up on your band stands a notch or two above the lower member holes as you may not have room to maneuver the steel in to place once all of the props are in place!
Do see our slide show on our web site that shows the whole process albeit quite quickly but there is a pause and rewind facility on the slide show.
Measure the depth of the socket in the top hole to the outer side of the outer skin (Y) now offer up a size 0 prop from the sole plate to the lower hole and roughly set the height to that hole to make it easier later on, Using 4 of the nuts and bolts supplied with 4 washers fix the first size 0 prop to the Sneedle Prop creating a “F shape” now 2 person lift the Sneedle Prop in to the top socket ensuring your measurement (Y) is met Now level the Sneedle prop both ways and tighten the first zero prop just so it is tight enough that it wont fall out (actual tightening up comes later). Bolt the second zero prop to the Sneedle prop inside of the building ensuring both props are sat nicely on their retrospective sole plates and again only tight enough to hold for now.
Now is the time to lift in to place the Load Plates and bolt through with the supplied nuts, bolts and washers, two per Sneedle Prop one to each side. these only need tightening with a normal spanner, not over tightening.
Repeat this process for all of the Sneedles Now the top of the Sneedles can be fixed together with the supplied bracing and connectors, followed by fixing all the lower arms together with supplied bracing, then at this point the diagonal bracing can be fixed to either end in opposite directions, then screw the size zero prop's base plates to the timber sole plates (The Props are now Laterally restrained) Now inspect the top holes and make sure the outer brick work is supported as with any form of needling slate packing will be required in places to ensure all is supported you may find that the top arm has taken the inside skin only usually caused by drilling at a downward angle so just ensure this is packed above the prop with slate.now the outer props can be tightened first, Remember you are holding the masonry not lifting it, then for the internal prop this wants to be pulled up to steady the system and certainly not too tight.
It is now safe to remove the outer skin brick/block work for the steel, Once this is done a close inspection can be made to ensure the internal blockwork is supported and slate where required.(this could be the opposite of the above mentioned if the core drilling was aimed upwards slightly) Now the internal block work can be safely removed.
Fit new steel in place on whatever pad stones requested brick up and dry pack as you would a conventional needling job. Leave for 48 hours then the Sneedle Props can be safely removed and all brickwork can be made good Sneedle Prop’s Extensions These are for use for when a picture frame steel set up is going to be used to give an extra 300 mm reach to the lower member to allow space for a trench to be dug… Simply bolt the extension steel to the base of the Sneedle Prop with the lower holes for the acrows ensuring that the extension is the right way around i.e. 300mm further inside the existing room, then affix the acrows in the same manner as stated above noting that the acrows are now 300mm further apart favoring the inside of the existing building.
HEALTH AND SAFETY (This section must be read by all Hirer’s of Sneedle Props.)
Sneedle Props Are ONLY to be used for Domestic 2 Storey Dwellings.
Prior to using any Sneedle Props; You should identify that this is a suitable method to carry out the planned work, if unsure consult a structural engineer. You must identify all loadings that the Sneedle props will have to support including loads from a floor above which could have heavy furniture etc., a roof including tiles, a water tank in the loft, a full bath, or even people walking around above etc. as you would with any form of needling.
We state that only one opening to be created at a time within one length of wall. If a corner of a building is to be removed a structural engineer should be approached, as the loads would need to be calculated. There is a process that should be followed for this, of fitting one steel first completely, then the second steel can be safely fitted. It should be checked that the masonry and any timbers are in good condition prior to any knock through as remedial work may be needed first.
You should obtain competent structural engineers’ advice, if there is any doubt about the condition of the structure or the nature of the loading or if any unusual loads are suspected.
Caution Sneedle Props are Heavy 40kg approx. (TWO PERSON LIFT) and may have sharp edges always wear protective clothing; gloves and protective foot wear.
Maximum load per Sneedle 400kg to be spaced at no more than 750mm centers to a maximum opening size of 7200mm you should get advice from a structural engineer if you have any doubts.
The contractor Must ensure the lateral stability of the building, the lateral stability of the Sneedle Props and the lateral stability of all supports during operation.
The spacing of the props is to be determined by the contractor or their Temporary works engineer.
Sneedle Props Registered Trade Mark
Sneedle Props Patent Pending GB 1902097.3
Web Site sneedleprops.com