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|01-08-2011, 09:38 PM||#1|
Join Date: Jan 2011
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How to repair main support beam
My cottage was built 30 years ago but I lived in for the past 20 years . Two floors and basement, which is irregular shaped approximately 42'x42'
In basement we have the Main support wood beam which lies on 3 iron supports plus the two concrete walls at the end. Distances between the supports are 12',9',10.5',10.5' starting from gas furnace room side to office room side. The main support beam is actually divided into two parts of lengths 31.5' and 10.5' starting from gas furnace room side . Both beams have a cross section of 19.5Cmx24Cm. House is OK so far no beam sag, except the usual small concrete walls, and foundation cracks , fixed in few places by professionals , never moved after, we live North on clay soil . Never looked at these support beams before , but chipping, due to humidity ..etc as the professionals ( contractors) said on one side of the beam ( call it good side)is there all over . cracks Widths up to 8mm, and depth of up to 6Cm into the beam. The other support beam side( call it good side) is covered with decoration and cannot tell, except in furnace room where we see small cracks starting to develop ( up to 2 mm width and 3 cm depth into the beam) on the good side. Also at the top and bottom of the beam we see up to 3 mm width and 3 cm depth cracks.
May be all cracks were there over the years but I never noticed them?? Also the bottom of the beam is not exactly horizontally levelled , it is listing or sloping or bottom dropping a little by maximum of 10mmfrom good side to bad side( but no longitudinal sagging over the 360Cm beam length). In May 2010 my friends( epoxy foundation cracks contractor, professor of civil engineering, and other contractors and inspector)and against their own self interest!! swore to me it is normal chipping and their houses are the same ? but the professor advised me to put small gypsum test patches and watch. Last May 2010, I put small test patches of gypsum on the cracks ,to see if the cracks are still moving??they did not for all of last summer, but Nov 2010 the test gypsum cracked slightly , meaning mobility ? or due to change of weather or due to furnace working again? or shut down of the humidifier? the parquetry on beam top( in the first house floor) also moves slightly as has been over the years. To repair if necessary the 360 Cm support beam part in the furnace room I am thinking, of course with your kind advice and employment of professional contractors, (the contractors should know but we may never know ?):
1. stitch at angles ( what angle) few screws, what length ? 30Cm ? what diameter? 5mm, what material ? stainless steel or fibre glass ? what separation, put more screws especially at the listing part or bottom dropping to lift it up by 10mm maximum ,so the beam would become horizontal levelled and flush again? but I am afraid the beam will crack more at the other good side, and may be internally too??
since by the elapse of time the hard wood has solidified at its current slightly listing position.
2. Bond a steel plate dimension 1Cmx19.5Cmx360Cm, is 1Cm thickness solid enough to resist shear and bending ? by water based or other epoxy ? should the plate extend end to end over the full 360Cm span or could be shorter? should the plate rest on end supports like the housed concreted wall and another attached steel plate bolted to the concrete wall and iron support at the other end ,or this is not necessary? should the plate be also bolted to the beam bottom? what size and kind bolts or screws if necessary? ? again, I am afraid the beam will crack more at the other good side, and may be internally too?? I am 63 years old , if I fix my kidney , my stomach, sugar level and .. will complain !
3. For solution 1, add a steel strap ( like wrapping or like a belt)every one meter say to hold the beam together like a belt? use stainless steel or steel or fibre glass? what thickness 5 mm? what belt locking style?? what width 6Cm? this slightly avoids trying to return the beam to flush horizontally , which may fracture the other beam side., ie we leave the beam slightly listing but hold it together ?Also , By such strapping , we may not need screws an or bolts in solution 2 ? do we just bond the belt by epoxy around the beam or use bolt or screw again?
or will such belts chock the old beam ???
4. For which of the solutions above we can insert fibre glass or carbon fibre strips or thin rods and epoxy filling into the cracks? so we may regain some of the beam strength lost to chipping? what epoxy? or adhesive water based
5. May be combining 3 and 4 yields another possible solutions to avoid hurting the old support beam by bolts and screws of solutions 1 and 2 ??
6. My engineering professor said two parallel bolted steel plates sandwiching my old support beam may create undesirable moments??? and they look like battle star Glactica? especially if the beam is already listing ( twisting, or bottom dropping )by a maximum of 1Cm from side to side
7. If the solution of steel plate in 2 is taken and it has to rest on end supports, could the contractor attach a steel I or U beam to the main post by clamps and bolts?. Then the I beam is welded to ? or just resting on steel plate which is bonded or by epoxy ( or bolted ) to the house ground foundation at the footing. The steel plate ( glued or belted to the support beam )will rest on the top cross section of the I beam ? I hope we don't have to dig new foundation footing for the I beam , it will be firmly bolted to the existing iron post which rests on 1'x1' foundation footing ? presumably by the builder ?
Thanks for your professional help and advice to help me and the contractor , whatever your kind time permits
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