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Home My WebLink AboutConstruction Observation 10.18.2022A*rdersonlfl$tructural W¿þEngineering October 18,2022 Ms. Robyn Whaley t776 County Road 241 New Castle, CO 8L647 ffi €.Äßl'ng.u¿l Gü#{TT6'{tthtlfiHr¡ñsHf RE: ADU lnspection - t776 County Road 24L - New Castle, CO. Dear Ms. Whaley: Regarding the referenced structure, Anderson Structural Engineering, lnc. visited the site on October LO,2022 to inspect existing conditions. We understand the structure was built around 1.994 and additions were completed in 2020. Our findings and analysis follow below; Background The subject ADU is a one story wood framed structure. The main level is a slab on grade and the foundation consists of concrete stem walls bearing on spread footings and isolated sonotube footings. The roof is wood framed. The originalstructure measured approximately L4'-4" x24'- 0". A continuous gable roof structure continued over an outdoor patio area measuring approximately 20'-8" x24'-0". A subsequent addition involves adding exterior walls to create an enclosed structure measuring approximately 35'-0" x 24'-0". A wood framed shed roof was added over the entry. A site specific geotechnical report and framing / foundation plans were not available. Slte Condltions The structure is wood framed with wood siding exterior finish and gypsum board interior finish. Select areas of interior and exterior wall finish were removed for inspection and an attic access panel was removed. The exterior shows continuously sheathed wood panel construction consisting ol 7 f L6" OSB panels over 2 x 4 stud walls spaced at 16" o.c. /2" diameter anchor bolts were noted to be installed @ 56" o.c. Load bearing headers carrying roof trusses were noted to span 4'-0" and consisted of (2) 2 x LO's. The original covered exterior area utilizes two span (3) 2 x L0 beams supported by 6 x 6 posts. The beams span approximately 9'-4" and carry each end of the roof trusses. The roof trusses were 2x wood metal plate connected designs typical of engineered trusses. Light gage hurricane clips were noted to be installed at each end of the trusses. OSB sheathing is installed over the trusses. The shed roof construction consisted of 2x 6 rafters @ t6" o.c. with Simpson LUS24 hangers each end, Rafter span is approximately 5'-6". Rafters are supported at the exterior wall with a 2x ledger 823 Grand Ave. Suite 340 r Glenwood Springs, CO 81601 (970) 984-0320 o email: landon@anderson-structural.com Amderson[//structural V¿þEngineering fastened with (2) 16d nails @ t6'o.c. Rafters at the low end of the roof are supported by a (1) 2 x6beamspanningapproximatelyS'-T"between6xGposts.The2x6beamisattachedwith(2) 16d nails. Foundation inspection was limited to two observation holes. A hole in the rear of the structure indicates stemwall construction extending below the local code mandated frost depth of 36". The footing was noted to extend 4" past the stemwall. lnsulated concrete forms were used on the stem walls prohibiting inspection for wall cracking and distress. Sonotube foundations supporting 6 x 6 posts were noted to extend below the code mandated 36" frost depth. A light gage metal post base was noted to attach the posts to the foundation. The edge of the slab on grade was visible at the entry wall. The interior slab on grade was covered by finishes. The owner noted that the slab on grade was uncracked and in good condition at the time of the 2020 remodel.Thestudwallsaddedduringtheremodelol2O2Obearontheslabongrade. Nodistress was observed or noted by the owner. Analysis Visible structure was limited and assessment is primarily based on exposed observation areas, visible finishes and other signs of performance. Finishes were generally in good condition and no distress was noted. Analysis of the existing structure is in accordance with the 20L5 lnternational Building Code. Load bearing walls consisting of 2 x 4 studs @ L6" o.c. are acceptable for the current roof truss loading. Similarly, the continuous sheathed wall panels satisfy current code requirements for shear under wind and seismic loading. Window and door headers were checked using a roof dead load of 20 psf and the snow load requirement of 40 psf. We find the 4 ft. window headers to be adequate for this loading. Roof trusses could not be verified as they are specialty design provided by truss manufacturers. The appearance of the trusses is consistent with typical designs we have observed for similar buildings. The typical practice for truss manufacturers in L994lor this area would have been to provide engineered stamped truss designs to accommodate a snow load of 40 psf. No distress was noted and the roof framing was dry and in good condition, Adequate uplift restraint was provided with installed clips. Roof beams from the original construction were checked for the truss loading. The (3) 2 x L0 beams were found to be overstressed for the code mandated snow load of 40 psf. We recommend adding an addition al 2 x LO ply to the face of the beam. The additional ply shall be attached the existing beam with (2) %" x6" simpson SDS screws @ L6" o.c. The ends of the ply can be cut short of the walls and posts and are not required to bear on the supports. The shed roof addition was checked for a dead load of L0 psf and a snow load of 40 psf. The 2 x 6 rafters are acceptable for a5'-6" span. Simpson 1U524 hangers are acceptable as well as the ledger connection to the building. We find the (L) 2 x 6 rim beam to be overstessed for the 8'-7" 823 Grand Ave. Suite 340 o Glenwood Springs, CO 81601 (970) 984-0320' emuil: landon@anderson-structural.cortt Amderson///S,tructural \[¿þEngineering span. We recommend adding an additional ply of 2 x 6 to the face of the existing beam. The new ply should be nailed to the existing ply with L0d nails @ L2" o.c. staggered. The connection for each beam end should be reinforced with (31%" x 5" Simpson SDS screws installed through the l2l 2x6 beam into the 6 x 6 post. Foundation observation shows adequate frost depth per current code requirements. Foundation loading is light. The excavation indicates a 16"wide footing. This should provide adequate bearing assuming a bearing pressure of 1500 psf per the prescriptive code using clay soils. The floor slab on grade was not visible due to applied finishes. The slab on grade for this building is not considered structural. The load bearing structures are frost protected on the stemwalls and sonotube foundations; however, the partition walls constructed during the 2020 addition bear on the slab which is not frost protected. While there is potential for movement, this should not effect the structural systems. The owner should monitor interior finishes for signs of movement. Recommendations Based on our analysis above we recommend the following; L. lnstall an additional 2 x L0 ply to existing (3) 2 x L0 roof beams. 2. lnstall an addition al 2 x 6 play to the existing (1-) 2 x 6 shed roof beam. 3. Monitor new partition walls for any signs of movement due to frost heave Limitations The inspection described above was limited to visible observation of exposed structural elements. Limited demolition was conducted to reveal hidden areas. No test¡ng of materials was conducted. Assessment and recommendations are based on our field assessment of existing conditions and our structural engineering experience with similar types of construction and materials. Please do not hesitate to call our office for any additional questions. Singerely, IrË Landon Anderson, P.E. Anderson Structural Engineering, lnc. 823 Grand Ave. Suite 340 o Glenwood Springs, CO 8L601 (970) 984-0320 . em ai I : la ndon (ðanderson-structural.com 35435 p'l â'2L