An enclosed pool with no humidity control and with inadequate ventilation to the outside is not a satisfactory environment for timber. It would not be proper for many other materials in the same building or for the swimmers.
Structural roof supports, whether they be beams, arches, trusses or the roof decking can be subjected to near 100% relative humidity if there is no provision made for ventilation. Dehumidification systems for relative humidity control are available. For large enclosures this would be the more costly method and not simple to maintain.
Wood should not be loaded in tension perpendicular to grain. Construction details must be aware that there are no recognized tension perpendicular to grain design values.
Do not load wood in tension perpendicular to grain.
Do not hang deep beams on widely spaced bolts in tightly fitted holes from bottom to top of beam. Shrinkage can result in tension perpendicular to grain. Use the good compression strength of wood in a supporting shoe and with just sufficient bolts to take care of uplift.
For pitched and tapered curved beams (PTC) an additional design consideration is radial tension. The radial tension allowable design stress for southern pine glued laminated PTC beams is one-third the horizontal shear allowable.
Pools Page 3